Srimad Bhagavatam Canto 05, Chapter 06, Text 03

SB 5.6.3

tatha coktam —
na kuryat karhicit sakhyam
 manasi hy anavasthite
yad-visrambhac cirac cirnam
 caskanda tapa aisvaram
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
All the learned scholars have given their opinion. The mind is by nature very restless, and one should not make friends with it. If we place full confidence in the mind, it may cheat us at any moment. Even Lord Siva became agitated upon seeing the Mohini form of Lord Krsna, and Saubhari Muni also fell down from the mature stage of yogic perfection.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
The first business of one trying to advance in spiritual life is to control the mind and senses. As Sri Krsna says in Bhagavad-gita (15.7):
mamaivamso jiva-loke
 jiva-bhutah sanatanah
manah sasthanindriyani
 prakrti-sthani karsati
Although the living entities are part and parcel of the Supreme Lord and are therefore in a transcendental position, they are still suffering in this material world and struggling for existence due to the mind and the senses. To get out of this false struggle for existence and become happy in the material world, one has to control the mind and senses and be detached from material conditions. One should never neglect austerities and penances; one should always perform them. Lord Rsabhadeva personally showed us how to do this. In the Srimad-Bhagavatam (9.19.17) it is specifically stated:
matra svasra duhitra va
 naviviktasano bhavet
balavan indriya-gramo
 vidvamsam api karsati
A grhastha, vanaprastha, sannyasi and brahmacari should be very careful when associating with women. One is forbidden to sit down in a solitary place even with one’s mother, sister or daughter. In our Krsna consciousness movement it has been very difficult to disassociate ourselves from women in our society, especially in Western countries. We are therefore sometimes criticized, but nonetheless we are trying to give everyone a chance to chant the Hare Krsna maha-mantra and thus advance spiritually. If we stick to the principle of chanting the Hare Krsna maha-mantra offenselessly, then, by the grace of Srila Haridasa Thakura, we may be saved from the allurement of women. However, if we are not very strict in chanting the Hare Krsna maha-mantra, we may at any time fall victim to women.
Srimad Bhagavatam Canto 05, Chapter 06, Text 02
Srimad Bhagavatam Canto 05, Chapter 06, Text 04