Ibn Umar (RAA) narrated that the Messenger of Allah (ﷺ) said:
"If anyone seeks refuge in Allah's name, grant him protection; if anyone asks you for something in Allah's name give him something; and if anyone does you a favor recompense him, but if you do not have the means to do so, make Dua (supplication) for him." Related by Al-Baihaqi. (IT)
English reference (IT): Book 16, Hadith 1510 (IT)
Arabic reference (IT): Book 16, Hadith 1467 (IT)