 In his visit to Syria in 637 to receive surrender of Jerusalem, Amr ibn al-Aas tried to convince Umar for the invasion of Egypt, but Umar rejected on the ground that Muslim rule in Syria was still not firm.After the great plague in 639, Umar paid a visit to Syria and was again persuaded by Amr for the invasion of Egypt.Along with various other reasons, Amr convinced Umar that Byzantine influence in Egypt is a continuous threat to Muslim rule in Palestine and that Egypt is the richest land on earth that can provide Muslims with immense wealth, economical stability and strategic location for trade with North Africa and Mediterranean.