Nasai

Imam al-Nasa'i rahimahullah's intent from the present and previous chapters is that worldly people consider lineage and ancestry as the basis for relationships, whereas in Islam, religion, knowledge, and piety (taqwa) have been declared the basis of virtue. Therefore, taking worldly lineage and ancestry into account is not necessary in marriage; rather, religious lineage is considered valid. Some individuals have also regarded lineage and ancestry as valid under the term "kafa’ah" (compatibility), but this can only be given secondary importance, not primary. In other words, if after religion and piety, lineage and ancestry are also found, then it is good; otherwise, the real foundation of marriage is religion. Therefore, a marriage between a free person and a slave can take place if both are Muslims.