The Prophet (ﷺ) said, "The two months of `Id i.e. Ramadan and Dhul-Hijja, do not decrease (in superiority).
Sahih al-Bukhari Book 30, Hadith 22
← Previous Hadith Allah's Messenger (ﷺ) vowed to keep aloof from his wives for one month, and he had dislocation of his leg. So, he stayed in a Mashruba for 29 nights and then came down. Some people said, "O Allah's Messenger (ﷺ)! You vowed to stay aloof for one month," He replied, "The month is of 29 days."

Sahih al-Bukhari Book 30, Hadith 21 Next Hadith → The Prophet (ﷺ) said, "We are an illiterate nation; we neither write, nor know accounts. The month is like this and this, i.e. sometimes of 29 days and sometimes of thirty days."

Sahih al-Bukhari Book 30, Hadith 23