Ibn Abi Najih narrates from Mujahid (may Allah have mercy on him) concerning the saying of Allah: "And give its due on the day of its harvest." [Surah al-An'am: 141], that it means giving from it on the day the crop is cut. He showed with a gesture of his hand a palmful or two, as if he were giving something: at the time of harvesting, giving a handful or two handfuls. He was gesturing with his hand as if grasping something, and he would say: They would give a handful, and they would leave them (the poor) to follow behind the harvesters' traces. A group holds that this verse has been abrogated by the obligation of zakah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7507