God did not need to tempt Abraham to see Abraham's faith, let's look at the story again.
In verse 2 of Genesis 22, it is recorded that God called Abraham and set him to sacrifice Isaac, but let's see from verse 11:
And the angel of the LORD called unto him out of heaven, and said, Abraham, Abraham: and he said, Here am I. And he said, Lay not thine hand upon the lad, neither do thou any thing unto him: for now I know that thou fearest God, seeing thou hast not withheld thy son, thine only son from me. (Genesis 22:11-12)
Was it God? He feared God and did not with hold his only son from me, who? The angel. Let's not forget that in the old testament, Satan the devil was not often identified.
And again the anger of the LORD was kindled against Israel, and he moved David against them to say, Go, number Israel and Judah. (2 Samuel 24:1)
Now this verse seems to suggest God moved David to sin, but let's look at another report of same incident:
And Satan stood up against Israel, and provoked David to number Israel. (1 Chronicles 21:1)
Now if we don't know God, we accept the first report, but indeed it was the devil. The same who tempted Jesus.
In the New Testament, the devil and deceiver is exposed, so we know that the temptations were not of God, hence James 1:13:
Let no man say when he is tempted, I am tempted of God: for God cannot be tempted with evil, neither tempteth he any man: