Prayers and Meditations — Paragraph 548
Source (Arabic)
تَزَلْ كُنْتَ مُقْتَدِرًا وَلا تَزالُ تَكُونُ مُهَيْمِنًا لا يَعْزُبُ عَنْ عِلْمِكَ مِنْ شَيْءٍ، وَإِنَّكَ أَنْتَ المُقْتَدِرُ
Translation
Thou art He Whose power is from everlasting to everlasting. Nothing escapeth Thy knowledge. Thou art, verily, the God of power, the God of glory and wisdom.