"Nothing veils the saying of 'There is no god except Allah' except what comes out of the mouth of the one who has mustaches on the night of the middle of Shaʿbān."
السيوطي ٢٥٩٦٤a:
«لَا يَحْجُبُ قَوْلَ لَا إِلَهَ إلا الله عَنِ الله إلا مَا خَرَجَ مِنْ فَمِ صَاحِبِ الشاربين لَيلَةَ النِّصْفِ مِنْ شَعْبَانَ۔»