Wa alaykum salam wa rahmatuLlahi wa barakatuHu,
Marrying any number more than four is not permissible. In the time of the Prophet (upon him be peace) there were companions who embraced Islam while married to more than four wives, and in each instance the Prophet (upon him be peace) commanded them to only retain four by separating from the others. Perhaps some confusion arises when reading the verse:
فَانكِحُوا مَا طَابَ لَكُمْ مِنَ النِّسَاءِ مَثْنَى وَثُلَاثَ وَرُبَاعَ
“Marry from the women who are good for you; two, three, or four.” (Nisa’ 3)
In the verse, the intent is not to join between the mentioned numbers; rather, it is for “takhyir.” Meaning, one may marry two or three or four. (Kifayat al-Nabih 13/136)
Moreover, limiting polygyny to four wives is a point of scholarly consensus (ar. ijma’). (al-Mawsu’at al-Fiqhiyyah al-Kuwaitiyyah 5/113)
And Allah knows best.
Answered by: Shaykh Yaqub Abdurrahman