I mean the -abad found in place names like Faisalabad, Allahabad and Hyderabad. This suffix is from Persian آباد ābād "city, building, habitation; cultivated, peopled", from Indic *paH- "protect, keep". It's cognate with Sanskrit pā "to watch, keep, preserve".
The Proto-Indo-European root is *peh₂- "protect, feed", which in English became food, feed and fodder. In Latin it became pāstor "shepherd".