Matthew Poole and continuators on Genesis 50:23

23 And Joseph saw Ephraims children, of the third generation : the children also of Machir the son of Manasseh, were brought up upon Josephs knees .

Reckoning from and after Ephraim, i. e. Ephraims Grandchildrens children. So early did Ephraims priviledge above Manasseh appear, and Iacobs blessing, Gen. 48. 19. take place.

Heb. Sons. For though he had but one Son, viz. Giiead by his first wife, yet he married a second Wife, and by her had two other Sons, 1 Chron. 7. 16. which Ioseph lived long enough to [illegible: 1+ letters]ee. Or under the name of children his grandchildren also might be comprehended. So there is no need of that Enallage of Sons for one Son, which we meet with in other places.

Laid upon Iosephs lap or knees, where Parents use ofttimes to take up and repose their Infants, to express their love to them and delight in them. And some observe, that it was an antient custom, in divers Nations that the Infant as soon as it was born was laid upon the Grandfathers knees. So it is an Ellipsis whereby one word is put for two, or under one Verb. See more of this phrase on Gen. 30. 3. and 48. 12.

Marginal references: Numb. 32. 39; Heb. born.