'Forever' in the Bible

Therefore the Lord God of Israel declares, ‘I did indeed say that your house and that of [Aaron] your father would walk [in priestly service] before Me forever.’ But now the Lord declares, ‘Far be it from Me—for those who honor Me I will honor, and those who despise Me will be insignificant and contemptible.

You will look at the distress of My house (the tabernacle), in spite of all the good which God will do for Israel, and there will never again be an old man in your house.

But I will raise up for Myself a faithful priest who will do according to what is in My heart and in My soul; and I will build him a permanent and enduring house, and he will walk before My anointed forever.

Now I have told him that I am about to judge his house forever for the sinful behavior which he knew [was happening], because his sons were bringing a curse on themselves [dishonoring and blaspheming God] and he did not rebuke them.

Therefore I have sworn to the house of Eli that the sinful behavior of Eli’s house (family) shall not be atoned for by sacrifice or offering forever.”

Samuel said to Saul, “You have acted foolishly; you have not kept the commandment of the Lord your God, which He commanded you, for [if you had obeyed] the Lord would have established your kingdom over Israel forever.

You shall never cut off your lovingkindness and faithfulness from my house, not even when the Lord cuts off every one of the enemies of David from the face of the earth.”

As for the agreement of which you and I have spoken, behold, the Lord is between you and me forever [making sure that we each keep our word].”

Jonathan told David, “Go in safety, inasmuch as we have sworn to each other in the name of the Lord, saying, ‘The Lord shall be between me and you, and between my descendants and yours forever.’” Then he stood and left, while Jonathan went into the city.