Jefferson was known to sell slaves when he needed money. More important, though, is the fact that upon his death he only freed Sally Hemmings' family. The rest of his slaves--130 of them--were auctioned off.
To John W. EppesMonticello June 30. [18]20.
I consider a woman who brings a child every two years as more profitable than the best man of the farm. what she produces is an addition to capital, while his labors disappear in mere consumption...(Farm Book, 45-46).
It is relevant that Jefferson died rather deeply in debt. His creditors had a claim on his slaves, so he wasn’t really free to emancipate them.
OTOH, he could have lived a little less lavishly and gotten out of debt so he could free his slaves.
G. Washington unostentatiously not only freed but made financial provision for the care of his slaves in his will.