Parashas Eikev · Passuk 7:13
[God] will favor you and bless you and multiply you—blessing your issue from the womb and your produce from the soil, your new grain and wine and oil, the calving of your herd and the lambing of your flock, in the land sworn to your fatherscfathers See note at 1.35. to be assigned to you.
Torah Temimah points to Chullin 84b.
TT lemma: ועשתרות צאנך (unit 2 of 2).
English: Rav Chisda said: What is meant by “ashterot of your flock”? That they enrich their owners. From here R’ Yochanan said: One who wishes to become wealthy should occupy himself with small cattle.
Custom (wordplay / ashtarot → wealth)
The unusual term for flock is tied to enrichment, grounding counsel about livelihood in small cattle.