It is narrated from Fatimah bint Husayn bin Ali (may Allah have mercy on her) that the Messenger of Allah (peace and blessings be upon him) said: "The one who asks has a right, even if he comes riding on a horse."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الصدقات / 13204