Hazrat Ali a.s Has said that When You sight the Moon Do Not Leave Your  Place Till You recite  This Dua. 
BISMILLAAHIR RAHMAANIR RAHEEM. 
ALLAAHUMMA INNEE AS-ALOKA KHAYRA HAAZASH SHARE WA FATAHAHU WA NOORAHU WA BASARAHU WA BARAKATAHU WA ZAHURAHU WA RIZKAHU WA AS-ALOKA KHAYRA MAA BA'DAHU WA A-0'OZOBEKA MIN SHAREE MAA FEEHE WA SHAREE MAA BA'DAHU. ALLAAHUMMA AD-KHILO A'LAYNAA BIL AMNE WAL EEMAANE WAS-SALAAMATE WAL ISLAAME WAL BARAKATE WAT-TAQWAA WAT-TAWFEEQE LEMAA TOHIBBO WA TARZA WA SALLAL LAAHO A'LAA MOHAMMADIN WA AALE MOHAMMAD.
