Parashas Eikev · Passuk 7:14
You shall be blessed above all other peoples: there shall be no sterile male or female among you or among your livestock.
Torah Temimah points to Bekhorot 44b.
TT lemma: ובבהמתך (unit 2 of 3).
English: Resh Lakish said: What is meant by “There shall not be among you a barren one or a barren female, or among your animals”? When will there not be a barren one among you? When [you are careful even] regarding “your animals” — taken to teach that a person may not delay relieving himself even in public, lest he endanger himself or become barren.
Custom (bodily care derived from the verse)
The promise of fertility is linked to basic care of the body, including not holding back natural needs.