Zayd bin Wahb (may Allah have mercy on him) narrates: We were sitting with Sayyiduna Hudhayfah (may Allah be pleased with him) in the mosque when a man entered through one of the gates of Kindah and began to pray a prayer in which he was not completing its bowing and prostration. Sayyiduna Hudhayfah (may Allah be pleased with him) asked him: "Since when have you been praying this prayer?" He replied: "For forty years." He said: "You have not (really) prayed for forty years, and if you had died (in this state), you would have died upon something other than the fitrah (way) of Abu al-Qasim (peace and blessings be upon him)."
Hadith Referenceالمعجم الأوسط / باب الألف / 1718
Hadith Takhrij«أخرجه البخاري فى «صحيحه» برقم: 389، 791، 808، وابن حبان فى «صحيحه» برقم: 1894، والنسائي فى «المجتبى» برقم: 1311 / 1، والنسائي فى «السنن الكبرى» برقم: 611، 1236، والبيهقي فى «السنن الكبرى» برقم: 2772، 4066، وأحمد فى «مسنده» برقم: 23730، 23840، والبزار فى «مسنده» برقم: 2817، 2819، 2899، وعبد الرزاق فى «مصنفه» برقم: 3733، 3732، وابن أبي شيبة فى «مصنفه» برقم: 2983، 4702»