SB 7.12.7
varjayet pramada-gatham
agrhastho brhad-vratah
indriyani pramathini
haranty api yater manah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
A brahmacari, or one who has not accepted the grhastha-asrama [family life], must rigidly avoid talking with women or about women, for the senses are so powerful that they may agitate even the mind of a sannyasi, a member of the renounced order of life.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Brahmacarya essentially means the vow not to marry but to observe strict celibacy (brhad-vrata). A brahmacari or sannyasi should avoid talking with women or reading literature concerning talks between man and woman. The injunction restricting association with women is the basic principle of spiritual life. Associating or talking with women is never advised in any of the Vedic literatures. The entire Vedic system teaches one to avoid sex life so that one may gradually progress from brahmacarya to grhastha, from grhastha to vanaprastha, and from vanaprastha to sannyasa and thus give up material enjoyment, which is the original cause of bondage to this material world. The word brhad-vrata refers to one who has decided not to marry, or in other words, not to indulge in sex life throughout his entire life.