Does Paul mis-quote Genesis about 'offspring'? [duplicate]

Question

In Galatians 3, Paul tells us that the promises to Abraham include a reference to 'offspring' (singular) rather than 'offsprings' (plural) or descendants.

¹⁶Now the promises were made to Abraham and to his offspring. It does not say, “And to offsprings,” referring to many, but referring to one, “And to your offspring,” who is Christ. _ESV

However the promises as recorded in Genesis don't seem to back that up, such as this from chapter 22:

¹⁵And the angel of the Lord called to Abraham a second time from heaven ¹⁶and said, “By myself I have sworn, declares the Lord, because you have done this and have not withheld your son, your only son, ¹⁷I will surely bless you, and I will surely multiply your offspring as the stars of heaven and as the sand that is on the seashore. And your offspring shall possess the gate of his enemies, ¹⁸and in your offspring shall all the nations of the earth be blessed, because you have obeyed my voice.” _ESV

Is Paul misquoting Genesis or re-interpreting it or something else?

Answer 1

And in thy seed shall all the nations of the earth be blessed, because thou hast hearkened to my voice." Genesis 22:18 LXX kai eneuloghqhsontai en tw spermati sou panta ta eqnh ths ghs anq¢ wn uphkousas ths emhs fwnhs

Note the use of the singular seed (spermati) Paul probably has in mind the LXX translation of the verse . Anyway, offspring can be understood as singular and collective noun