It is narrated from Sayyiduna Ali (may Allah be pleased with him) that he said (in supplication): "O Allah, indeed You know that no one of this Ummah worshipped You before me after its Prophet (peace and blessings be upon him), and I worshipped You at a time when no (other) individual of this Ummah had begun to worship You, that is, six years before that."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from al-Ajlah except Amr."
Hadith Referenceالمعجم الأوسط / باب الألف / 1746
Hadith Takhrij«أخرجه الحاكم فى «المستدرك» برقم: 4612، والنسائي فى «السنن الكبرى» برقم: 8339، وأحمد فى «مسنده» برقم: 787، والطيالسي فى «مسنده» برقم: 184، وأبو يعلى فى «مسنده» برقم: 447، والبزار فى «مسنده» برقم: 751، والطبراني فى «الأوسط» برقم: 7427»