What is the ruling of Islamic law on marrying a person one of whose parents or relatives is of unknown lineage, or who belongs to simple professions, or who is from outside the tribe, and are the jurisprudential rulings affected by pre-Islamic cultures related to competence in different societies?

Describing the ijtihad (definition) (independent reasoning) of a scholar as "rubbish" is unfitting for a Muslim. Those qualified among the people of knowledge are rewarded for their ijtihad; the one who is correct receives two rewards, and the one who errs receives one reward, as stated in the Hadith (definition). Competence (kafa'ah) in marriage is a matter of scholarly disagreement, and the preponderant opinion is that it is restricted to religion. Thus, a righteous Muslim man is competent for any Muslim woman. The rationale behind considering competence is sound, and the disagreement lies in whether it is a condition for the validity or the continuity of the contract. Competence provides reasons for stability and harmony in the family and avoids discord. Therefore, the opinion that requires competence has its validity.