Sunan Abi Dawud 18
سنن أبي داود#18SahihNarrated A'ishah:The Apostle of Allaah ( sal Allaahu alayhi wa sallam ) used to remember Allaah, the Great and Majestic, at all moments
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiSahih Muslim (373)
In-book reference: 1:18