Temporary marriage for a married person, when he is absent

Question:

When should a husband enter into a temporary marriage when he is married?

Answer:
Al-Fath Ibn Yazid reported that he asked Imam Ar-Rida (a.): “What is it with the temporary marriage (Mut’ah)?” He said: “It is allowed (Halal) and absolutely permissible for the one to whom God did not give the marriage so that he would remain chaste through the temporary marriage, but when there is no need for him because he is in a marriage, then it is allowed to him, when he is absent from her.” [Al-Kafi of Al-Kulaini, Volume 5 Page 273 Hadith 2]

عن علي بن إبراهيم عن المختار بن محمد ومحمد بن الحسن عن عبد الله بن الحسن عن الفتح بن يزيد أنه سأل الإمام الرضا عليه السلام عن المتعة فقال: هي حلال مباح مطلق لمن لم يغنه الله بالتزويج فليستعفف بالمتعة فإن استغنى عنها بالتزويج فهي مباح له إذا غاب عنها