It is narrated from Sayyidah Asma bint Abi Bakr (may Allah be pleased with her) that she said: I prepared a bag of travel provisions for the Prophet (peace and blessings be upon him) in the house of Abu Bakr (may Allah be pleased with him), when he (peace and blessings be upon him) intended to emigrate to Madinah. She said: "We could not find anything with which to tie the provision bag and the waterskin. So I said to Abu Bakr (may Allah be pleased with him): By Allah, I find nothing to tie it with except my waistband." He said: Tear it into two pieces; tie the waterskin with one and the bag with the other. So she did so, and for that reason she was called "Dhat al-Nitaqayn", that is, the one with the two waistbands.
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20580