It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever seeks refuge in the name of Allah, grant him refuge; whoever asks you in the name of Allah, give to him; whoever invites you, accept his invitation; whoever does good to you, repay him; and if you do not find anything with which to repay him, then pray for him so much that you feel you have repaid him."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 5365