NASAI-KUBRA 10599:
from Jābir b. ʿAbdullāh —
"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).'" (Using translation from Ibn Mājah 3800)
الكبرى للنسائي ١٠٥٩٩:
عن جابر بن عبد الله —
سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ «إِنَّ أَفْضَلَ الذِّكْرِ لَا إِلَهَ إِلَّا اللهُ وَأَفْضَلُ الدُّعَاءِ الْحَمْدُ لِلَّهِ»