Albert Barnes Commentary Psalms 73:27

"For, lo, they that are far from thee shall perish: Thou hast destroyed all them that play the harlot, [departing] from thee." — Psalms 73:27 (ASV)

For, behold, those who are far from you will perish - All that are estranged from you; all who are not your friends. They will certainly be destroyed. For them there can be no hope. This is the fact which solved the difficulty of the psalmist in regard to the divine dealings with people (Psalms 73:3–7). The fact that there will be a righteous judgment, in which God will deal with people according to their deserts, made everything clear. Compare Psalms 73:16-20.

You have destroyed - That is, You will certainly destroy. The psalmist places himself in the future, and speaks of this as if it were already done. It will be so certainly done that he could speak of it as if it were already accomplished.

All those who go a whoring from you - The relation of God to His people is often compared in the Scriptures with the marriage relation (compare Psalms 45); and a departure from Him is compared with a lack of faithfulness to the marriage contract. See Matthew 12:39; Matthew 16:4; Jeremiah 3:8–9; Jeremiah 5:7; Jeremiah 13:27; Ezekiel 23:37; and Revelation 2:22.