"Estimate for it (11)" means: restrict the count for it, based on the saying of the Almighty: {And whoever is restricted in his provision} (12), meaning: it was restricted for him, and His saying: {He expands provision for whom He wills and restricts (it)} (13). The restriction for it is that Sha'ban be made twenty-nine days. Ibn 'Umar has interpreted it through his own action, and he is its narrator and most knowledgeable of its meaning; therefore, it is mandatory to return to his interpretation, just as it was returned to in the interpretation of separation in the option of the two transacting parties. It was narrated from 'Imran (14), may Allah be pleased with him, that the Messenger of Allah (may Allah bless him and grant him peace) said to a man: "Have you fasted anything from the end of Sha'ban?" He said: "No." And in another wording: "Have you fasted anything from the 'sarar' (latter days) of this month?" He said: "No." He said: "Then if you break your fast, fast two days." Agreed upon (15). The 'sarar' of the month is its end, the nights (16) in which the crescent is concealed and does not appear. And because it is doubt in one of [the two ends of the month that has not appeared] (17) therein to be from other than Ramadan, so fasting is mandatory just like the other end.