It was narrated from Ibn 'Umar,:
from the Prophet, concerning a man who had a wife then divorced her, then another man married her but divorced her before consummating the marriage. Could she go back to the first man? He said: "No, not until he tastes her sweetness." (JA)
English reference (JA): Vol. 3, Book 9, Hadith 1933 (JA)
Arabic reference (JA): Book 9, Hadith 2008 (JA)