His works would be part of his sanctification which Reformed treat separately from justification.
Please, please do me a favor. Look at what Scripture alone says and use your God-given reason to understand what it is saying:
“Was not Abraham our father ***justified ***by works when he offered up his son Isaac on the altar? You see that faith was active along with his works, and faith was completed by his works; *and the Scripture was fulfilled that says, “Abraham believed God, and it was counted to him as righteousness”—and he was called a friend of God.*You see that a person is ***justified ***by works and not by faith alone.*And in the same way was not also Rahab the prostitute ***justified ***by works when she received the messengers and sent them out by another way?” - James 2:21-25 ESV
Do me another favor; do not go to a Protestant commentary, do not even go to a Catholic and/or Orthodox commentary. Do not go to a Catechism or Confession of some sort. Simply look at what the Bible alone states. If you see the word, ‘sanctification’ instead of ‘justification’ in the passage I included from a Protestant Bible, then I will concede.
The sacrifice of Isaac is described as a test of Abraham after which God told Abraham that He now knew he feared Him. God did not need to test Abraham to know this.
“Oh, let the evil of the wicked come to an end,
****and may you establish the righteous—
you who test the minds and hearts,
****O righteous God!” Psalm 7:9 ESV
“I know, my God, that you test the heart and have pleasure in uprightness.” 1 Chronicles 29:17 ESV
“**ut just as we have been approved by God to be entrusted with the gospel, so we speak, not to please man, but to please God who tests our hearts.” 1 Thessalonians 2:4 ESV
“Prove me, O Lord, and try me;
****test my heart and my mind.” - Psalm 26:2 ESV
That fits in with the view, that in James, Abraham’s justification before men was what was being dealt with.
“And he said to them, “You are those who justify yourselves before men, but God knows your hearts. For what is exalted among men is an abomination in the sight of God.” Luke 16:15 ESV
“Beware of practicing your righteousness before other people in order to be seen by them, for then you will have no reward from your Father who is in heaven." Matthew 6:1 ESV
In light of these two verses of Scripture, how can you purport, “Abraham’s justification before men was what was being dealt with”?**