Sahih Ibn Khuzaymah

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the poor companions came to the Messenger of Allah (peace and blessings be upon him) and said, “O Messenger of Allah, the wealthy have attained high ranks and everlasting blessings due to their wealth. They pray as we pray, they fast as we fast, and they have extra wealth with which they perform Hajj, ‘Umrah, strive in jihad, and give charity.” So the Prophet (peace and blessings be upon him) said: “Shall I not tell you of an action which, if you act upon it, you will catch up with those who have surpassed you, and those who come after you will not be able to catch up with you? (You will always remain ahead of them in reward and virtue.) After every prayer, recite « سُبْحَانَ اللَٰه » thirty-three times, « الحَمْدُ لِلَٰه » thirty-three times, and « اللهُ أَكْبَرُ » thirty-three times.” He says that then there was a difference among us; some of us said that we would recite « سُبْحَانَ اللَٰه ، الحَمْدُ لِلَٰه » thirty-three times and « اللهُ أَكْبَرُ » thirty-four times. Therefore, I went again to the Messenger of Allah (peace and blessings be upon him), and he said: “Continue reciting « سُبْحَانَ اللَٰه ، الحَمْدُ لِلَٰه ، اللهُ أَكْبَرُ » until you have completed all of them thirty-three times each.”