It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever is given something good, let him accept it and then also repay it; and whoever does not have the means to repay it, let him praise him. Whoever praises him has, as it were, thanked him, and whoever conceals it has, as it were, been ungrateful; and whoever displays something as a gift when it was not given to him is like one who wears two garments of falsehood."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 12031