SB 9.19.11

sambaddha-vṛṣaṇaḥ so ’pi
 hy ajayā kūpa-labdhayā
kālaṁ bahu-tithaṁ bhadre
 kāmair nādyāpi tuṣyati
Word for word: 
sambaddha-vṛṣaṇaḥ — rejoined with his testicles; saḥ — he; api — also; hi — indeed; ajayā — with the she-goat; kūpa-labdhayā — whom he got from the well; kālam — for a time; bahu-titham — of a long, long duration; bhadre — O my dear wife; kāmaiḥ — with such lusty desires; na — not; adya api — even until now; tuṣyati — is satisfied.
Translation: 
My dear wife, when the he-goat had his testicles restored, he enjoyed the she-goat he had gotten from the well, but although he continued to enjoy for many, many years, even now he has not been fully satisfied.
Purport: 

When one is bound by affection for one’s wife, one is attached to sexual desires that are very difficult to overcome. Therefore, according to Vedic civilization, one must voluntarily leave his so-called home and go to the forest. Pañcāśordhvaṁ vanaṁ vrajet. Human life is meant for such tapasya, or austerity. By the austerity of voluntarily stopping sex life at home and going to the forest to engage in spiritual activities in the association of devotees, one achieves the actual purpose of human life.