It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the delegation of Abd al-Qays came to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Welcome, O delegation." They said: O Messenger of Allah, we are a clan of Rabi'ah, and the disbelievers of Mudar stand between us and you, and we can reach you only in a sacred month, so give us a command that we may adopt and to which we may invite those behind us. The Messenger of Allah (peace and blessings be upon him) said: "I command you with one thing and forbid you four: faith in Allah, bearing witness that there is no god except Allah and that Muhammad is the Messenger of Allah, establishing prayer, paying zakah, and that you pay the khumus (one-fifth) of whatever spoils you gain. And I forbid you the dubba', the naqir, the hantam and the muzaffat."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12898