It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him): the Prophet (peace and blessings be upon him) came out while I was sitting moving my lips, and he (peace and blessings be upon him) said: "Why are you moving your lips?" I said: O Messenger of Allah, I am remembering Allah. He (peace and blessings be upon him) said: "Shall I not tell you of something which, if you said it and then strove at it night and day, you still would not reach it?" I said: Of course. He (peace and blessings be upon him) said: "Say: All praise is for Allah, as many as His Book has counted; and all praise is for Allah, as much as is in His Book; and all praise is for Allah, as many as His creation has counted; and all praise is for Allah, as much as is in His creation; and all praise is for Allah, the fill of His heavens and His earth; and all praise is for Allah, to the number of all things; and all praise is for Allah, the fill of all things. And say tasbih and takbir in the same way."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 8091