Srimad Bhagavatam Canto 07, Chapter 11, Text 16

SB 7.11.16

varta vicitra salina-
 yayavara-siloñchanam
vipra-vrttis caturdheyam
 sreyasi cottarottara
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
As an alternative, a brahmana may also take to the vaisya’s occupational duty of agriculture, cow protection, or trade. He may depend on that which he has received without begging, he may beg in the paddy field every day, he may collect paddy left in a field by its proprietor, or he may collect food grains left here and there in the shops of grain dealers. These are four means of livelihood that may also be adopted by brahmanas. Among these four, each of them in succession is better than the one preceding it.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
A brahmana is sometimes offered land and cows in charity, and thus for his livelihood he may act in the same way as a vaisya, by cultivating land, giving protection to cows and trading off his surpluses. A better process, however, is to pick up grains from a field or from a dealer’s shop without begging.
Srimad Bhagavatam Canto 07, Chapter 11, Text 15
Srimad Bhagavatam Canto 07, Chapter 11, Text 17