“Mohammed had prepared an army to invade the borders of Syria. When Mohammed died Abu Bakr sent an army headed by Usama Ibn Zayd and ‘Umar Ibn al-Khattab. The army marched towards southern Palestine and invaded some parts of the land, frightened the people and captured some booty. …By the end of the year 12, Hajira Abu Bakr became interested in Syria (Al Sham). He issued orders to four of his great generals and designated for each one of them a country which he was given to invade. He assigned Damascus to Yazid, Jordan to Sharhabil, Homs to Abu ‘Ubayda and Palestine to ‘Umru Ibn al-’As.”- in “The Rightly Guided Caliphs” by Dr. Abu Zayd Shalabi