All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
It is known that the Prophet, sallallaahu ‘alayhi wa sallam, had eleven wives and passed away leaving behind nine living wives. All marriages of the Prophet, sallallaahu ‘alayhi wa sallam, had valid and legitimate purposes. Some scholars held that it is recommended to take a second wife; some even maintained that it is incumbent on the man to take a second wife if he is unable to maintain his chastity and his first wife does not satisfy his sexual needs, on condition that he can treat them justly. Ibn Qudaamah wrote, “In marriage, people are of three categories. Some men may fear to fall into temptation if they do not marry. According to the majority of jurists, it is obligatory on such a man to marry in order to guard himself against what is unlawful....” [Al-Mughni]
It should be noted that there is no difference in this regard between the first or second marriage; the Hanbali scholar Al-Mardaawi wrote, “It is recommended that he confines himself to marrying only one wife if he is sexually satisfied and able to preserve his chastity, according to the preferred opinion of the Hanbali Mathhab. Ibn Al-Jawzi said: ‘unless he is not satisfied with only one wife.’ It was also said that it is recommended to take a second wife as in the case he is not satisfied with only one. This is what is apparent from the pronouncement of Imaam Ahmad. He maintained that in this case, he should borrow money (if financially unable) and take a second wife; then there is hope that he will escape (temptation).” [Al-Insaaf]
Allaah Knows best.