John Gill Commentary Genesis 47:29

"And the time drew near that Israel must die: and he called his son Joseph, and said unto him, If now I have found favor in thy sight, put, I pray thee, thy hand under my thigh, and deal kindly and truly with me: bury me not, I pray thee, in Egypt;" — Genesis 47:29 (ASV)

And the time drew nigh that Israel must die
As all men must, by the appointment of God, even good men, the Israel of God; though they shall not die a spiritual death, nor an eternal one, yet a corporeal one, which is for their good, and is a blessing to them; the sting being removed, and so not a penal evil, which is owing to Christ's dying for them, who has abolished death as such; and there is a time fixed for their death, beyond which they must not live, and before which they must not die, but when the time comes there is no avoiding it; the time of Jacob's death was drawing on, as he perceived by the great decline of his natural strength, and perhaps by a divine impulse on his mind:

and he called his son Joseph ;
sent for him, by a messenger, to come to him:

and said unto him ;
when he was come:

if now I have found grace in your sight ;
which is not spoken in a way of submission, as from an inferior to a superior, as the phrase is sometimes used; or as signifying what would be esteemed as a favour should it be granted, but it is as if he should say, if you have any filial affection for me as a parent, and are willing to show love and respect to me, do as follows:

put, I pray you, your hand under my thigh :
a gesture in swearing, as Jarchi observes, (Genesis 24:2Genesis 24:3) ; adding, for explanation's sake,

and deal kindly and truly with me ;
"kindly", by promising and swearing to do what he after desires; and "truly", by observing his oath, and fulfilling his promise:

bury me not, I pray you, in Egypt ;
not choosing to lie among idolaters at death, with whom he cared not to have any fellowship in life.