إِذَا قَدَرُوا عَلَى الزَّادِ وَالرَّاحِلَةِ فَاضِلًا عَنْ مَسْكَنِهِ
Translation: When they have the means for provisions and transport beyond their necessary home.
Idhā introduces a temporal condition, qadarū is a verb with plural subject suffix, and ʿalā al-zād is a prepositional complement. Fāḍilan expresses the surplus qualification.