Jami` at-Tirmidhi 2334
جامع الترمذي#2334SahihAnas bin Malik narrated that that the Messenger of Allah(s.a.w) said:"This is the son of Adam, and this is his life-span." And he placed his hand at the (height of the) nape of his neck, then he extended it (higher) and said:" From there is what is hoped for, from there is what is hoped for
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih
Al-AlbaniSahih
Bashar Awad MaaroufHasan Sahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 36:31