Srimad-Bhagavatam: Canto 9 - Chapter 1 - Verse 51

Sanskrit:

एवं वर्षसहस्राणि मन:षष्ठैर्मन:सुखम् ।विदधानोऽपि नातृप्यत् सार्वभौम: कदिन्द्रियै: ॥ ५१ ॥

ITRANS:

evaṁ varṣa-sahasrāṇimanaḥ-ṣaṣṭhair manaḥ-sukhamvidadhāno ’pi nātṛpyatsārva-bhaumaḥ kad-indriyaiḥ

Translation:

Although Mahārāja Yayāti was the king of the entire world and he engaged his mind and five senses in enjoying material possessions for one thousand years, he was unable to be satisfied.

Purport:

The kad-indriya, or unpurified senses, can be purified if one engages the senses and the mind in Kṛṣṇa consciousness. Sarvopādhi-vinirmuktaṁ tat-paratvena nirmalam. One must be freed from all designations. When one identifies himself with the material world, his senses are impure. But when one achieves spiritual realization and identifies himself as a servant of the Lord, his senses are purified immediately. Engagement of the purified senses in the service of the Lord is called bhakti. Hṛṣīkeṇa hṛṣīkeśa-sevanaṁ bhaktir ucyate. One may enjoy the senses for many thousands of years, but unless one purifies the senses, one cannot be happy.