Hamzah bin Abi Usayd (may Allah have mercy on him) narrates from his father (Sayyiduna Abu Usayd (may Allah be pleased with him)) that the Messenger of Allah (peace and blessings be upon him) said on the Day of Badr, when we had lined up against Quraysh and they had lined up against us: "When they come close to you, shoot them with arrows." These are the words of al-Fadl's hadith; Abu Ahmad says in his hadith: "idha akthabukum", that is: "When they come quite close to you, shower them with arrows, and save your arrows." Abu Bakr said: The correct word is "akthabukum".
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18475