If he who buys milk is proud, he who sells it should be prouder.

What it means
The proverb sets the buyer's pride beside the seller's. If having the milk is something to be proud of, the one who had it to sell has more reason still.
Wolof · West Africa
Source and context
From: Wolof, West Africa
Source: Wolof (Senegal) oral-tradition proverb; no. 2 in African Manners, "Wolof Proverbs: 146 in Total" (africanmanners.wordpress.com), with the Wolof in an old transcription: "Sou sipou ngabo guennetey pate". Earlier recorded here as from Richard Shawyer, "Wisdom of the Wolof Sages" (2009); that book has not been checked.

The meaning given here is our own reading. Other interpretations exist.