Sayyiduna Talhah Ibn ‘Ubaydullah رضى الله تعالى عنه narrates: Verily when the Prophet صلى الله تعالى عليه وسلم saw the new moon, he would say: اللهم أهله علينا بالأمن والإيمان، والسلامة والإسلام، ربى وربك الله، هلال رشد وخير
Allawhumma Ahillahu ‘Alaynaa bil Amni wal Imaan, was Salaamati wal Islam, Rabbee wa Rabbukallawh, Hilaalu Rushdin wa Khayrin
O ALLAH. Let this new moon appear before us with peace & faith, and with security & Islam, my Sustainer and your Sustainer is ALLAH TA’ALA, let this moon be one of goodness & guidance. (Tirmizi)
The above Du’aa should be made, when the moon 🌙 is sighted.