SB 11.17.41

pratigrahaṁ manyamānas
 tapas-tejo-yaśo-nudam
anyābhyām eva jīveta
 śilair vā doṣa-dṛk tayoḥ
Synonyms: 
pratigraham — accepting charity; manyamānaḥ — considering; tapaḥ — of one’s austerity; tejaḥ — spiritual influence; yaśaḥ — and fame; nudam — destruction; anyābhyām — by the other two (teaching Vedic knowledge and performing sacrifice); eva — indeed; jīveta — a brāhmaṇa should live; śilaiḥ — by collecting rejected grains in the field; — or; doṣa — the discrepancy; dṛk — seeing; tayoḥ — of those two.
Translation: 
A brāhmaṇa who considers that accepting charity from others will destroy his austerity, spiritual influence and fame should maintain himself by the other two brahminical occupations, namely teaching Vedic knowledge and performing sacrifice. If the brāhmaṇa considers that those two occupations also compromise his spiritual position, then he should collect rejected grains in agricultural fields and live without any dependence on others.
Purport: 

A pure devotee of the Lord should always remember that the Supreme Personality of Godhead will personally take care of him. As the Lord states in Bhagavad-gītā (9.22):

ananyāś cintayanto māṁ
 ye janāḥ paryupāsate
teṣāṁ nityābhiyuktānāṁ
 yoga-kṣemaṁ vahāmy aham

“But those who worship Me with devotion, meditating on My transcendental form — to them I carry what they lack and preserve what they have.”

A brāhmaṇa should not become a professional beggar for his personal maintenance. In India there are many so-called brāhmaṇas who sit at the gates of important temples and beg from everyone who comes and goes. If someone does not give a donation they become angry and chase that person. Similarly, in America there are many big preachers who collect huge amounts of money by begging on television and radio. If a brāhmaṇa or Vaiṣṇava considers that being a professional beggar is weakening his austerity, destroying his spiritual influence and giving him a bad reputation, then he should give up that process. One may beg everyone to contribute to the cause of the Supreme Personality of Godhead, but one will be diminished in austerity, influence and reputation by begging for one’s personal livelihood. A brāhmaṇa may then take up the task of teaching Vedic knowledge and performing sacrifice. But even such occupations do not bring one to the highest platform of trust in God. A brāhmaṇa who teaches as a means of livelihood may often be curbed in his teaching, and one who performs sacrifice may be manipulated by materialistic worshipers. In this way, a brāhmaṇa may be placed in an embarrassing and compromised position. Therefore a high-class brāhmaṇa or Vaiṣṇava ultimately will depend completely on the mercy of the Lord for his maintenance. The Lord promises to maintain His devotee, and an advanced Vaiṣṇava never doubts the word of the Lord.