All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
It is impermissible for a man to marry his wife’s sister as long as his marriage is still intact; it is prohibited for a man to marry two sisters at the same time, whether they are full sisters or half-sisters. The prohibition in this regard was established by the Quran, Sunnah texts, and Ijma’ (scholarly consensus of opinion). As for the evidence from the Quran, Allah, The Exalted Says (what means): {… and that you take [in marriage] two sisters simultaneously...} [Quran 4:23]
As for the Sunnah, it is authentically reported that Umm Habeebah bint Abu Sufyan said to the Prophet, sallallahu ‘alayhi wa sallam, “O Messenger of Allah! Marry my sister, the daughter of Abu Sufyan.” He, sallallahu ‘alayhi wa sallam, said: “Do you like that?” She replied: “Yes, for even now I am not your only wife; and the most beloved person to share the good with me is my sister.” He, sallallahu ‘alayhi wa sallam, said: “But that is not lawful for me (i.e., to be married to two sisters at the same time.)” [Al-Bukhari and Muslim]
As for the Ijma', Al-Qurtubi said in his Tafseer: “The Muslim Ummah unanimously agreed that it is invalid for a man to conclude a marriage contract with a woman and her sister at the same time.”
These texts were of a general indication and did not make a distinction between full sisters and half-sisters on the father’s side or the mother’s side.
What further emphasizes the general indication of these texts is the wisdom behind this prohibition, which is the fear that it would lead to severing the ties of kinship due to the quarrels and disputes that occur between co-wives, mostly because of jealousy. The Prophet, sallallahu ‘alayhi wa sallam, referred to this wisdom in the Hadith narrated by Ibn Abbas that he, sallallahu ‘alayhi wa sallam, forbade marrying a woman and her maternal or paternal aunt at the same time and said: “If you do so, you will cut off your ties of kinship!” [At-Tabrani]
Hadith scholars questioned the authenticity of this Hadith’s chain of narration, but its meaning is correct.
Allah knows best.