It is narrated from Sayyiduna Mu'awiyah bin Haydah (may Allah be pleased with him) that he heard the Prophet (peace and blessings be upon him) saying: "Whoever is asked by his mawla (kinsman) for some of his surplus wealth and does not give it to him, it will be transformed on the Day of Resurrection into a bald serpent."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17027