لاَ إِلَهَ إِلاَّ أَنْتَ سُبْحَانَكَ إِنِّي كُنْتُ مِنَ الظَّالِمِينَ

There is none worthy of worship but You, glory is to You. Surely, I was among the wrongdoers.

Laa 'ilaaha 'illaa 'Anta subhaanaka 'innee kuntu minadh-dhaalimeen.

At-Tirmithi 5/529. Al-Hakim declared it authentic and Ath-Thahabi agreed with him 1/ 505. See also Al-Albani, Sahih At-Tirmithi 3/168.