It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "When the new crescent sets before the twilight (shafaq) has disappeared, it belongs to that one night; and when it remains on the horizon until after the twilight and then sets, it belongs to two nights (that is, it is the second night's moon)."
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب الصيام / 995
Hadith Gradingمحدثین:إسناده ضعيف
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :إسناده ضعيف. » «انفرد به المصنف من هذا الطريق»