Musannaf Ibn Abi Shaybah

Hazrat Mujahid says that Allah Almighty’s command { وَآتُوا حَقَّہُ یَوْمَ حَصَادِہِ } is: When you reap the harvest and the needy come to you, then give something for them as well; and when you gather (the crops, etc.), then give something for them; and when you heap it up, then give something for them; and when you clean it and begin to measure it, then give something (such as husks, etc.) for them. And when you have measured it and know how much it is, then pay its zakat. And when you pluck dates from the date palm, then leave some unripe and ripe dates for them, and when you begin to measure them, then also give something for them; and when its weight is known, then pay its zakat. (10580 M) It is narrated from Hazrat Dhahhak in the commentary of this verse that the calculation of its zakat will be on the day the crop is measured.