Sahih al-Bukhari 4583

Narrated 'Aisha:

The necklace of Asma' was lost, so the Prophet sent some men to look for it. The time for the prayer became due and they had not performed ablution and could not find water, so they offered the prayer without ablution. Then Allah revealed (the Verse of Tayammum).

حَدَّثَنَا مُحَمَّدٌ، أَخْبَرَنَا عَبْدَةُ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتْ هَلَكَتْ قِلاَدَةٌ لأَسْمَاءَ فَبَعَثَ النَّبِيُّ ﷺ فِي طَلَبِهَا، رِجَالاً فَحَضَرَتِ الصَّلاَةُ وَلَيْسُوا عَلَى وُضُوءٍ. وَلَمْ يَجِدُوا مَاءً، فَصَلَّوْا وَهُمْ عَلَى غَيْرِ وُضُوءٍ، فَأَنْزَلَ اللَّهُ. يَعْنِي آيَةَ التَّيَمُّمِ.