203
اللَّهُمَّ إِنِّي أَعُوذُ بِكَ أَنْ أُشْرِكَ بِكَ وَأَنَا أَعْلَمُ، وَأَسْتَغْفِرُكَ لِمَا لَا أَعْلَمُ
Allahumma inni a'udhu bika an ushrika bika wa ana a'lam, wa astaghfiruka lima la a'lam
O Allah, I seek refuge in You from associating anything with You while I know it, and I ask Your forgiveness for what I do not know.
Source Musnad Aḥmad 19606 (similar wording)
Compiler cites Aḥmad 4/403 and others; see Ṣaḥīḥ al-Jāmiʿ 3/233 and Ṣaḥīḥ at-Targhīb 1/19