Expedition of Ubaydah ibn al-Harith

In April 623, the Islamic prophet Muhammad sent Ubaydah ibn al-Harith with a party of sixty armed Muhajirun to the valley of Rabigh, in modern-day Saudi Arabia. They expected to intercept a Quraysh caravan that was returning from Syria under the protection of Abu Sufyan ibn Harb and 200 armed riders.Haykal, M. H.. Translated by al-Faruqi, I. R. A.. The Life of Muhammad, p. 256. Chicago: North American Trust Publications. The Muslim party travelled as far as the wells at Thanyat al-Murra, where Sa`d ibn Abi Waqqas shot an arrow at the Quraysh. This is known as the first arrow of Islam. Despite this surprise attack, "they did not unsheathe a sword or approach one another," and the Muslims returned empty-handed; however, two Meccans traders left their caravan, became Muslim, and went with the expedition back to Medina.

Timing

Some say that Ubaydah ibn al-Harith was the first to whom Muhammad gave a banner on a military expedition; others say Hamza was the first.
Some scholars assert that Muhammad sent out the expedition while he was in Al-Abwa' or upon his return to the Medina from the raid of Al-Abwa'.