Selah is used mostly in the Psalms. It is normally stated to be a time to pause, reflect or meditate on what has gone before. BUT Selah or Sela as mentioned in the Isaiah passage above from the Amplified Bible is actually a place!
In fact, it has three meanings in the Hebrew. (1) As a suspension (of music) or pause. (2) A ragged rock, stony or stronghold - from an unused root meaning to be lofty; a craggy rock, literally or to mean a fortress. And, (3) simply, a rock - a city in Edom, the same as cela’ or Sela, the rock-city of Idumaea. So, it's Sela in Hebrew, Petra in Arabic and Greek and means rock in English. All can thus be seen to denote a (rock-)city of Idumaea, just in the territory of Edom or a pause for reflection in the Psalm.
Here are a few more Scriptures showing what and where it is. I am using the Amplified Bible giving extra definition:
Isaiah 16:1.) "You [Moabites, now fugitives in Edom, which is ruled by the king of Judah] send lambs to the ruler of the land, from Sela or Petra through the desert and wilderness to the mountain of the Daughter of Zion [Jerusalem]."
2 Kings 14:7.) "Amaziah slew of Edom in the Valley of Salt 10,000, and took Sela (Greek petra [rock]) by war, and called it Joktheel, which is the name of it to this day."
Obadiah 1:1-3
THE VISION of Obadiah. Thus says the LORD God concerning Edom: we have heard tidings from the LORD, and an ambassador is sent forth among the nations [saying], arise, and let us rise up against [Edom] for battle! Behold, I will make you small among the nations [Edom]; you shall be despised exceedingly. The pride of your heart has deceived you, you dweller in the refuges of the rock [Petra, Edom’s capital], whose habitation is high, who says in his heart, who can bring me down to the ground?"
Let's now look through the ? 76 times it is mentioned in the Psalms and 3 times in Habakkuk. Do you see anything new now through reading the different definitions above? SO LETS LOOK THROUGH AND DISCERN WHICH DEFINITION IS BEING USED IN EACH CASE.
Habakkuk.
(Habakkuk 3:3.) "God [approaching from Sinai] came from Teman [which represents Edom] and the Holy One from Mount Paran [in the Sinai region]. Selah! His glory covered the heavens and the earth was full of His praise."
(Habakkuk 3:9.) "Your bow was made quite bare; sworn to the tribes [of Israel] by Your sure word were the rods of chastisement, scourges, and calamities. Selah! With rivers You cleaved the earth [bringing forth waters in dry places]."
(Habakkuk 3:13.) "You went forth and have come for the salvation of Your people, for the deliverance and victory of Your anointed [people Israel]; You smote the head of the house of the wicked, laying bare the foundation even to the neck. Selah!"
Psalms.
(Psalm 3:2.) "Many are saying of me, There is no help for him in God. Selah [pause, and calmly think of that]!"
Psalm 3:4.) "With my voice I cry to the LORD, and He hears and answers me out of His Holy Hill. Selah!"
(Psalm 3:8.) "Salvation belongs to the LORD; may Your Blessing be upon Your people. Selah!"
(Psalm 4:2.) "O you sons of men, how long will you turn My honour and Glory into shame? How long will you love vanity and futility and seek after lies? Selah!"
((Psalm 4:4.) "Be angry [or stand in awe] and sin not; commune with your own hearts upon your beds and be silent (sorry for the things you say in your hearts). Selah!"
(Psalm 7:5.) "Let the enemy pursue my life and take it; yes, let him trample my life to the ground and lay my honour in the dust. Selah!"
(Psalm 9:16.) "The LORD has made Himself known; He executes judgment; the wicked are snared in the work of their own hands. Higgaion [meditation]. Selah!"
(Psalm 9:20.) "Put them in fear [make them realise their frail nature], O LORD, that the nations may know themselves to be but men. Selah!"
(Psalm 20:3.) "Remember all your offerings and accept your burnt sacrifice. Selah!"
(Psalm 21:2.) "You have given him his heart’s desire and have not withheld the request of his lips. Selah!"
(Psalm 24:6.) "This is the generation [description] of those who seek Him [who inquire of and for Him and of necessity require Him], who seek Your Face, [O God of] Jacob. Selah]!"
(Psalm 24:10.) "Who is [He then] this King of Glory? The LORD of Hosts, He is the King of Glory. Selah!"
(Psalm 32:4.) "For day and night Your hand [of displeasure] was heavy upon me; my moisture was turned into the drought of summer. Selah!"
(Psalm 32:5.) "I acknowledged my sin to You, and my iniquity I did not hide. I said, I will confess my transgressions to the LORD [continually unfolding the past till all is told]—then You [instantly] forgave me the guilt and iniquity of my sin. Selah!"
(Psalm 32:7.) "You are a hiding place for me; You, LORD, preserve me from trouble, You surround me with songs and shouts of deliverance. Selah!"
(Psalm 39:5.) "Behold, You have made my days as [short as] handbreadths, and my lifetime is as nothing in Your sight. Truly every man at his best is merely a breath! Selah!"
(Psalm 39:11.) "When with rebukes You correct and chasten man for sin, You waste his beauty like a moth and what is dear to him consumes away; surely every man is a mere breath. Selah!"
(Psalm 44:8.)"In God we have made our boast all the day long, and we will give thanks to Your Name Forever. Selah!"
(Psalm 46:3.) "Though its waters roar and foam, though the mountains tremble at its swelling and tumult. Selah!"
(Psalm 46:7.) "The LORD of Hosts is with us; the God of Jacob is our Refuge (our Fortress and High Tower). Selah!"
(Psalm 46:11.) "The Lord of hosts is with us; the God of Jacob is our Refuge (our High Tower and Stronghold). Selah!"
(Psalm 47:4.) "He chose our inheritance for us, the glory and pride of Jacob, whom He loves. Selah!"
(Psalm 48:8.) "As we have heard, so have we seen in the city of the LORD of Hosts, in the city of our God: God will establish it forever. Selah!"
(Psalm 49:13.) "This is the fate of those who are foolishly confident, yet after them men approve their sayings. Selah!"
(Psalm 49:15.) "But God will redeem me from the power of Sheol (the place of the dead); for He will receive me. Selah!"
(Psalm 50:6.) "And the heavens declare His righteousness (Rightness and Justice), for God, He is judge. Selah!"
(Psalm 52:3.) "You love evil more than good, and lying rather than to speak Righteousness, Justice, and Right. Selah!"
(Psalm 52:5.) "God will likewise break you down and destroy you forever; He will lay hold of you and pluck you out of your tent and uproot you from the land of the living. Selah!"
(Psalm 54:3.) "For strangers and insolent men are rising up against me, and violent men and ruthless ones seek and demand my life; they do not set God before them. Selah!"
(Psalm 55:7.) "Yes, I would wander far away, I would lodge in the wilderness. Selah!"
(Psalm 55:19.) "God will hear and humble them, even He Who abides of old—Selah!—because in them there has been no change [of heart], and they do not Fear, Revere, and Worship God."
(Psalm 57:3.) "He will send from Heaven and save me from the slanders and reproaches of him who would trample me down or swallow me up, and He will put him to shame. Selah! God will send forth His Mercy and Loving-Kindness and His Truth and Faithfulness."
(Psalm 57:6.) "They set a net for my steps; my very life was bowed down. They dug a pit in my way; into the midst of it they themselves have fallen. Selah!"
(Psalm 59:5.) "You, O LORD God of Hosts, the God of Israel, arise to visit all the nations; spare none and be not merciful to any who treacherously plot evil. Selah!"
(Psalm 59:13.) "Consume them in wrath, consume them so that they shall be no more; and let them know unto the ends of the earth that God rules over Jacob (Israel). Selah!"
(Psalm 60:4.) "[But now] You have set up a banner for those who fear and worshipfully revere You [to which they may flee from the bow], a Standard displayed because of the Truth. Selah!"
(Psalm 61:4.) "I will dwell in Your Tabernacle forever; let me find refuge and trust in the Shelter of Your Wings. Selah!"
(Psalm 62:4.) "They only consult to cast him down from his height [to dishonor him]; they delight in lies. They bless with their mouths, but they curse inwardly. Selah!"
(Psalm 62:8.) "Trust in, lean on, rely on, and have confidence in Him at all times, you people; pour out your hearts before Him. God is a Refuge for us (a Fortress and a High Tower). Selah!"
(Psalm 66:4.) "All the earth shall bow down to You and sing [praises] to You; they shall praise Your name in song. Selah!"
(Psalm 66:7.) "He rules by His Might forever, His Eyes observe and keep watch over the nations; let not the rebellious exalt themselves. Selah!"
(Psalm 66:15.) "I will offer to You burnt offerings of fat lambs, with rams consumed in sweet-smelling smoke; I will offer bullocks and he-goats. Selah!"
(Psalm 67:1.) "God be merciful and gracious to us and bless us and cause His Face to shine upon us and among us—Selah!"
(Psalm 67:4.) "O let the nations be glad and sing for joy, for You will judge the peoples fairly and guide, lead, or drive the nations upon earth. Selah!"
(Psalm 68:7.) "O God, when You went forth before Your people, when You marched through the wilderness—Selah!"
(Psalm 68:19.) "Blessed be the LORD, Who bears our burdens and carries us day by day, even the God Who is our Salvation! Selah!"
(Psalm 68:32.) "Sing to God, O kingdoms of the earth, sing praises to the LORD! Selah!"
(Psalm 75:3.) "When the earth totters, and all the inhabitants of it, it is I Who will poise and keep steady its pillars. Selah!"
(Psalm 76:3.) "There He broke the bow’s flashing arrows, the shield, the sword, and the weapons of war. Selah!"
(Psalm 76:9.) "When God arose to [establish] judgment, to save all the meek and oppressed of the earth. Selah!"
(Psalm 77:3.) "I [earnestly] remember God; I am disquieted and I groan; I muse in prayer, and my spirit faints [overwhelmed]. Selah!"
(Psalm 77:9.) "Has God [deliberately] abandoned or forgotten His graciousness? Has He in anger shut up His Compassion? Selah!"
(Psalm 77:15.) "You have with Your [Mighty] Arm redeemed Your people, the sons of Jacob and Joseph. Selah!"
(Psalm 81:7.) "You called in distress and I delivered you; I answered you in the secret place of thunder; I tested you at the waters of Meribah. Selah!"
(Psalm 82:2.) "How long will you [magistrates or judges] judge unjustly and show partiality to the wicked? Selah!"
(Psalm 83:8.) "Assyria also has joined with them; they have helped the children of Lot [the Ammonites and the Moabites] and have been an arm to them. Selah!"
(Psalm 84:4.) "Blessed (happy, fortunate, to be envied) are those who dwell in Your House and Your Presence; they will be singing Your Praises all the day long. Selah!"
(Psalm 84:8.) "O LORD God of Hosts, hear my prayer; give ear, O God of Jacob! Selah!"
(Psalm 85:2.) "You have forgiven and taken away the iniquity of Your people, You have covered all their sin. Selah [pause, and calmly realise what that means]!"
(Psalm 87:3.) "Glorious things are spoken of you, O City of God. Selah!"
(Psalm 87:6.) "The LORD shall count, when He registers the peoples, that this man was born there. Selah!"
(Psalm 88:7.) "Your wrath lies hard upon me, and You have afflicted me with all Your waves. Selah!"
(Psalm 88:10.) "Will You show wonders to the dead? Shall the departed Arise and Praise You? Selah!"
(Psalm 89:4.) "Your Seed I will establish forever, and I will build up Your Throne for all generations. Selah!"
(Psalm 89:37.) "It shall be established forever as the moon, the faithful witness in the heavens. Selah!"
(Psalm 89:45.) "The days of his youth have You shortened; You have covered him with shame. Selah!"
(Psalm 89:48.) "What man can live and shall not see death, or can deliver himself from the [powerful] hand of Sheol (the place of the dead)? Selah!"
(Psalm 140:3.) "They sharpen their tongues like a serpent’s; adders’ poison is under their lips. Selah!"
(Psalm 140:5.) "The proud have hidden a snare for me; they have spread cords as a net by the wayside, they have set traps for me. Selah!"
(Psalm 140:8.) "Grant not, O LORD, the desires of the wicked; further not their wicked plot and device, lest they exalt themselves. Selah!"
(Psalm 143:6.) "I spread forth my hands to You; my soul thirsts after You like a thirsty land [for water]. Selah!"
Amen.