Mujahid (may Allah have mercy on him) says concerning this verse, "O you who believe, spend of the good things you have earned" [Surah al-Baqarah: 267]: O you who believe, spend from the pure provision you earn; what is meant is trade.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10395