SB 5.6.2

ṛṣir uvāca
satyam uktaṁ kintv iha vā eke na manaso ’ddhā viśrambham anavasthānasya śaṭha-kirāta iva saṅgacchante.
Synonyms: 
ṛṣiḥ uvāca — Śukadeva Gosvāmī said; satyam — the correct thing; uktam — have said; kintu — but; iha — in this material world; — either; eke — some; na — not; manasaḥ — of the mind; addhā — directly; viśrambham — faithful; anavasthānasya — being unsteady; śaṭha — very cunning; kirātaḥ — a hunter; iva — like; saṅgacchante — become.
Translation: 
Śrīla Śukadeva Gosvāmī replied: My dear King, you have spoken correctly. However, after capturing animals, a cunning hunter does not put faith in them, for they might run away. Similarly, those who are advanced in spiritual life do not put faith in the mind. Indeed, they always remain vigilant and watch the mind’s action.
Purport: 

In Bhagavad-gītā (18.5) Lord Kṛṣṇa says:

yajña-dāna-tapaḥ-karma
 na tyājyaṁ kāryam eva tat
yajño dānaṁ tapaś caiva
 pāvanāni manīṣiṇām

“Acts of sacrifice, charity and penance are not to be given up but should be performed. Indeed, sacrifice, charity and penance purify even the great souls.”

Even one who has renounced the world and has taken sannyāsa should not renounce chanting the Hare Kṛṣṇa mahā-mantra. Renunciation does not mean that one has to renounce saṅkīrtana-yajña. Similarly, one should not renounce charity or tapasya. The yoga system for control of the mind and senses must be strictly followed. Lord Ṛṣabhadeva showed how severe types of tapasya could be performed, and He set an example for all others.