Al-Harith bin Yazid and Yazid bin Abi Habib, describing the conquest of Qaysariyyah, said: They bombarded it every day with sixty mangonels. This was in the time of Umar (may Allah be pleased with him), until it was conquered at the hands of Mu'awiyah and Abdullah bin Amr (may Allah be pleased with them both).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18122