The Prophet (peace and blessings be upon him) said:
"The purest earning is a man's working with his own hand, and every trade that is free of deceit and sin."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 1033
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[حم طب ك] عن رافع بن خديج [طب] عن ابن عمر. تخريج الترغيب ٣/٣.