Prayers and Meditations — Paragraph 821
Source (Arabic)
أَشْهَدُ بِوَحْدَانِيَّتِكَ وَفَرْدَانِيَّتِكَ وَبِأَنَّكَ أَنْتَ اللهُ لَا إِلَهَ إِلَّا أَنْتَ.
Translation
to recite these words: “I bear witness to Thy unity and Thy oneness, and that Thou art God, and that there is none other God beside Thee.”)