Sayyiduna Rafi' bin Khadij (may Allah be pleased with him) said: The delegations of the Arabs came to the Messenger of Allah (peace and blessings be upon him), and no delegation came to us that was harder-hearted, or more likely to be such that Islam had not settled in their hearts, than the delegation of Banu Hanifah.
Hadith Referenceالمعجم الكبير للطبراني / باب الراء / 4418