Sayyiduna Abdullah bin Ja'far (may Allah be pleased with them both) relates concerning these words: "La ilaha illallahul-Halimul-'Azim, subhanallahi Rabbil-'Arshil-Karim, wal-hamdu lillahi Rabbil-'alamin (There is no god but Allah, the Forbearing, the Magnificent; glory be to Allah, Lord of the Noble Throne; and all praise is for Allah, Lord of the worlds)." He said: the Messenger of Allah (peace and blessings be upon him) used to say: "Teach these words to your dying ones." The Companions said: O Messenger of Allah, then how are they for the living? He (peace and blessings be upon him) said: "Even better, even better."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13788