سنن نسائی · Hadith 2149

It was narrated from Saeed bin ‘Amr bin Saeed bin Abi Al-’As, that he heard Ibn ‘Umar narrate that the Prophet said: “We are an unlettered Ummah; we do not use computation or astronomical calculations. The month is like this, and this, and this,” and he held down his thumb the last time. “And the month is like this, and this, and this,” completing thirty. (Sahih)

Translated by Dr. Muhammad Muhsin Khan · Reviewed by Islamic University of Madinah · Published March 2020