Jami` at-Tirmidhi 253

جامع الترمذي#253Sahih

Abdullah bin Mas'ud narrated:"Allah's Messenger would say the Takbir for every lowering and raising, standing and sitting, and (so did) Abu Bakr and Umar

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 ZaiSahih

In-book reference: 2:105