The Secret Expedition to Abu Sufyan

When Qab heard the news he said, mockingly sarcastically, if Muhammad al-Sallam has really killed all of these people, then it is better to be inside the earth than outside of it. He formed an alliance with Abu Sufyan against the Prophet SallAllahu Alaihi Wa Sallam. The details of this alliance we have no idea, none of the books of Sirah mentioned because again this was something between the two of them and then he was killed shortly afterwards. What could this alliance be other than a surprise attack, other than a tactic what is to be done?