Dua when sighting the new crescent moon
TIRMIDHI 3451:
from Bilāl b. Yaḥyá b. Ṭalḥah b. ʿUbaydullāh from his father from his grandfather Ṭalḥah b. ʿUbaydullāh —
that when the Prophet ﷺ would see a crescent moon, he would say:
allāhumma ahlilhu ʿalaynā bi-al-yumni wa-al-īmān, wa-al-salāmati wa-al-islām, rabbī wa-rabbuka Allāh
(O Allah, bring it over us with blessing and faith, and security and Islam. My Lord and your Lord is Allah.)”
الترمذي ٣٤٥١:
عن بلال بن يحيى بن طلحه بن عبيد الله عن أبيه عن جده طلحه بن عبيد الله —
أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا رَأَى الْهِلاَلَ قَالَ:
«(اللَّهُمَّ أَهْلِلْهُ عَلَيْنَا بِالْيُمْنِ وَالإِيمَانِ وَالسَّلاَمَةِ وَالإِسْلاَمِ رَبِّي وَرَبُّكَ اللَّهُ)»