Ash-Shaykh Bin Baaz, rahimahullah, was asked the following question,

Question:

ما هو الدعاء الذي يقال عند رؤية الهلال؟

“What is the du’a that is to be said when sighting the crescent (i.e. the moon at the beginning of the month)?”

Answer:

لم يثبت في هذا حديث عن النبي ﷺ، جاء في عدة أحاديث فيها ضعف…

“There is no hadith authentic from the Prophet sallahu alayhi wa salam in regards to this. A number of hadiths has been reported concerning it. However, they contain weakness in their chains.” End translation. [Reference]

Translated by

AbdulFattaah Bin Uthman
Abu Fajr