Midrash su Salmi 37:18

"And the lifespan of Sarah was 100 years" (Gen. 23:1) - "Ad-nai is concerned with the days of the blameless and their portion lasts forever." (Psalms 37:18) Just as they are blameless, so too their years are blameless:[Sarah] at 20 years of age was like [she was] at 7 years of age regarding beauty, at 100 years of age [she was] like at 20 years of age regarding sin. Another interpretation: "Ad-nai is concerned with the days of the blameless", this is Sarah who was blameless in her actions. Rabbi Yochana said: just as a heifer is blameless, and their inheritance is eternal, as it is written: "And the lifespan of Sarah was 100 years" - why is there a need to repeat "the lifespan of Sarah" at the end? To teach you that the lives of the righteous are beloved by the Place both in this world and in the world to come.

And these are the days of the years of the life of Avraham (Bereishit 25:7). It's written, God knows the days of the pure, and their inheritance will be eternal (Tehillim 37:18). God knows the days of the pure: this is Avraham, as it is said And be pure. And their inheritance will be eternal - and these are the days of the years of the life of Avraham. That he adores the Holy Blessed One, who gives the righteous and writes them in the Torah, so that the inheritance of their days will be remembered forever: In ripe old age, old and satisfied (Bereishit 25:8). And Avraham perished (ibid.) - Rabbi Yehuda bar Ilai said, the original pious would suffer with intestinal disease for ten and twenty days, to say that illness clarifies. Rabbi Yehuda said, everyone of whom it is said "perish" died of intestinal disease. It's written, strength and beauty are her robes [and she laughs at the last day] (Mishlei 31:25) - every reward of the righteous is prepared for them for the future to come. The Holy Blessed One shows them, before they are in this world, all the reward which They will eventually give them in the world to come - and their souls are satisfied and they sleep. Rabbi Elazar says, it's like a banquet which a king prepared and invited guests, and showed them what they would eat and drink, and their souls are satisfied and they sleep - so too with the Holy Blessed One. They show the righteous before they are in this world their veentual reward, and they sleep, as it is said For now I would be lying down, silent (Iyov 3:13). That is to say, at the time of the departure of the righteous, the Holy Blessed One shows them the reward of their labour. When Rabbi Abahu slept, thirteen rivers of balsam were shown to him. He said to them, whose are these? They said to him, yours. He said, these are Abahu's? ...