It is narrated from Hazrat Zaid bin Thabit (may Allah be pleased with him) that once we were commanded to say Subhan Allah thirty-three times, Alhamdulillah thirty-three times, and Allahu Akbar thirty-four times after every obligatory prayer. Then an Ansari saw a dream in which someone asked him, "Did the Prophet (peace and blessings be upon him) command you to recite these tasbihat in this way after every prayer?" He replied, "Yes!" The person said, "Recite them twenty-five times each, and add twenty-five times La ilaha illallah to them." When morning came, he mentioned this dream to the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) said, "Do it in this way."