Musnad Abu Ya'la al-Mawsili 151:64

Muhammad narrated to us, Umar bin Ali narrated to us, from Sulayman bin Yasar, from Qays, from Alqamah, from Abdullah, from the Prophet, peace and blessings of Allah be upon him, who said: "Whoever lends a Muslim man a dirham twice, it is for him like the reward of giving them in charity once."