It is narrated from Sayyidah Aishah (may Allah be pleased with her); she said: When the incident of my necklace took place as it did, and the people of the slander said what they said, I went out with the Prophet (peace and blessings be upon him) on another military expedition, and my necklace fell again, until searching for it held the people back, and dawn broke. At this I had to hear from Abu Bakr whatever Allah willed. He said to me: "My daughter, on a journey you have become a hardship and a trial, and the people have no water." At this Allah sent down the concession of tayammum. Abu Bakr said: "By Allah, my daughter, as far as I know, you are indeed blessed."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19463