for an endless time : for all time: for a very long time: at all times.
H5769 olam – long duration, antiquity, futurity, for ever, ever, everlasting, evermore, perpetual
ancient time, long time (of past)
for ever, always, continuous existence, perpetual, everlasting, indefinite or unending future, eternity(of future)
G166 aiōnios – without beginning and end, that which always has been and always will be; without beginning; without end, never to cease, everlasting
Genesis 17:7 I will establish my covenant between me and you and your offspring after you throughout their generations for an everlasting (H5769) covenant, to be a God to you and to your offspring after you.
Exodus 3:15 God said moreover to Moses, “You shall tell the children of Israel this, ‘Yahweh, the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you.’ This is my name forever, and this is my memorial to all generations.
Exodus 31:16 Therefore the children of Israel shall keep the Sabbath, to observe the Sabbath throughout their generations, for a perpetual (H5769) covenant.
Jude 1:7 Even as Sodom and Gomorrah, and the cities around them, having, in the same way as these, given themselves over to sexual immorality and gone after strange flesh, are shown as an example, suffering the punishment of eternal (G166) fire.
From a Hebraic perspective, forever does not always mean forever. The most accurate definition of forever is; for an appointed time. In order to determine how long this appointed time is you have to look at the context in which the word forever or eternal is used. Genesis 17:7 and Exodus 3:15; 31:16 establish that the ‘forever’ period of time is “throughout their generations,” which means as long as there continue to be people born, what is being said will be in effect.
Jude 1:7 uses the Greek word for forever or eternal to describe the fire that destroyed Sodom and Gomorrah. Are Sodom and Gomorrah still burning today? In this case, forever or eternity doesn’t really mean forever. Sodom and Gomorrah burned for an appointed time until it was completely consumed, then the fire went out. If Sodom and Gomorrah really were burning for eternity, there’s no doubt that it would be a major tourist attraction today, but this is not the case.