Indeed, sucking one’s wife breasts is a controversial issue among Muslim scholars. Some of them say that if a husband sucks his wife’s breast several times in a way that he gets satisfied and the milk reaches his stomach, his wife will be forbidden for him. But, the majority of scholars view that the sucking that makes a woman unlawful to one is that which is given only within the first two years of his life.
In this regard, we would like to cite for you the following by the well-known Muslim scholar, Sheikh Yusuf Al-Qaradawi, in which he states the following: “During the life-time of the Prophet’s Companions (may Allah be pleased with them all) it happened that one of the Companions was making love with his wife, and in the course of love-making he (the Companion) sucked her breasts to the extent that some of the milk reached his stomach. Following that, the Companion went to Abu Musa Al-Ash`ari (may Allah be pleased with him) and asked him about the ruling. Replying the man, Abu-Musa Al-Ash`ari said that the man’s wife had become forbidden for him. (i.e., like his mother)

After that, the man went to ask `Abdullah Ibn Mas`ud (may Allah be pleased with him) about the same ruling and Ibn Mas`ud stated that there was nothing wrong with what happened. Ibn Mas`ud backed his argument by citing the Prophetic hadith, which clearly states that suckling is confined only to the two earlier years of a child. Ibn Mas`ud cited this Qur’anic verse: ‘Mothers shall suckle their children for two whole years; (that is) for those who wish to complete the suckling…’ (Al-Baqarah: 233)
The apparent meaning of the aforementioned verse is that the suckling, which may act as a cause of prohibition, is confined to the suckling during the first two years. After the elapse of the first two years, suckling is no longer a cause of prohibition.
Hearing the above argument, Abu-Musa Al-Ash`ari (may Allah be pleased with him) said: ‘Do not ask me while this erudite scholar is there to guide you.
In conclusion, sucking the wife’s breast, as far as Islam is concerned, does not render her unlawful for the husband.”
Moreover, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, adds: “The wife’s breast milk is intended for the baby, and not for the husband to consume. Although the husband is allowed to suck on it gently, he is not allowed to draw the milk in. According to some scholars, if he were to do so it would endanger the marriage relationship — if done five times. The Prophet (peace and blessings be upon him) said, ‘Avoid that which is doubtful’, for, ‘thereby one keeps his honor and religion intact.’
It is, therefore, important for the husband to refrain from such actions for we should do what is most pious and therefore safest.”