Complex sentence: Muhammad ibn Idris ash-Shafi'i (d.820), founder of the Shafi'i school of thought, was the first to permit offensive jihad, limiting this warfare against pagan Arabs only, not permitting it against non-Arab non-Muslims.
Split into simpler sentences: Muhammad ibn Idris ash-Shafi'i (d.820), founder of the Shafi'i school of thought, was the first to permit offensive jihad. He limited this warfare against pagan Arabs only, not permitting it against non-Arab non-Muslims.