Sunan Abu Dawood, Chapter: Purification (Kitab Al-Taharah)

The Apostle of Allah (peace_be_upon_him) sent Usayd ibn Hudayr and some people with him to search the necklace lost by Aisha. The time of prayer came and they prayed without ablution. When they returned to the Prophet (peace_be_upon_him) and related the fact to him, the verse concerning tayammum was revealed. Ibn Nufayl added: Usayd said to her: May Allah have mercy upon you! Never has there been an occasion when you were beset with an unpleasant matter but Allah made the Muslims and you come out of that.