Al-Aswad bin Yazid (may Allah have mercy on him) used to borrow from a merchant who was a freed slave (mawla) of the Nakha' tribe, and when his stipend came out he would repay him. When his stipend came out, al-Aswad said to him: If you wish, defer it for us, for we have other obligations to meet from this stipend. The merchant said: I will not do it. So al-Aswad paid him 500 dirhams in cash. When the merchant had received them, the merchant said: Here, take them back. Al-Aswad said: I asked you for this earlier and you refused. The merchant said: I heard you narrating from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Whoever lends something twice, it is for him equal to giving it in charity once."
Only Abdullah bin al-Husayn Abu Hariz, the judge of Sijistan, narrated it, and he is not strong.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10953