Risālah fī Ḥukm al-Iqtidā’ bī l-Mukhālif (PDF)
Attached is a manuscript of a risālah by Shaykh Raḥmatullāh as-Sindhī on performing ṣalāh behind an imām of a different madhhab (school of thought). This risālah was recently printed by Dar al-Moqtabas and it contained many errors. Note: The editor appears to be a Salafi