Sunan Ibn Majah 3800
سنن ابن ماجه#3800HasanJabir bin 'Abdullah said:"I heard the Messenger of Allah (ﷺ) say: 'The best of remembrance is La ilaha illallah (None has the right to be worshipped but Allah), and the best of supplication is Al-Hamdu Lillah (praise is to Allah)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniHasan
Muhammad Fouad Abd al-BaqiHasan
Shuaib Al ArnautHasan
Zubair Ali ZaiHasan
In-book reference: 33:144