It wasnarrated from Abu Hurairah that the Messenger of Allah (ﷺ)said:
"When you see the new crescent then fast, and when you see itthenstop fasting. If it is cloudy then fast thirty days." (JA)
English reference (JA): Vol. 1, Book 7, Hadith 1655 (JA)
Arabic reference (JA): Book 7, Hadith 1724 (JA)