It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that we were praying with the Prophet Muhammad (peace and blessings be upon him) when a man began to say «الله اكبر كبيرا ، والحمدلله كثيرا ، و سبحان الله بكرة واصيلا». After the prayer, the Prophet Muhammad (peace and blessings be upon him) asked, "Who said these words?" The man replied, "O Messenger of Allah! I said them." The Prophet Muhammad (peace and blessings be upon him) said: "I was amazed at these words, for all the gates of the heavens were opened for them." Sayyiduna Ibn Umar (may Allah be pleased with them both) says that since I heard this from the Prophet Muhammad (peace and blessings be upon him), I have never abandoned these words.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4627