Musnad Abu Ya'la al-Mawsili 140:8

Abu al-Rabi' al-Zahrani narrated to us, al-Salt—meaning Ibn Hajjaj—narrated to us, and al-Hajjaj al-Khasaf narrated to us, from Yazid al-Raqashi, from Anas, who said: The Messenger of Allah (ﷺ) said: "Whoever helps his brother with his need and treats him kindly, it is a right upon Allah that He shall have him served by the servants of Paradise."