Why does Paul say he is not speaking by commandment in 2 Corinthians 8:8?

Paul states he is not speaking by commandment to show his appeal for giving is not a direct divine command, but arises from the zeal of others and to prove the sincerity of their love. Even so, the Holy Spirit prompted his writing, making it inspired Scripture.

Les explains that Paul often says he is not speaking by commandment. The Lord had told Paul to tell the people certain things, yet once Paul wrote them, they became inspired Word of God. So even when Paul says this is not a commandment from God, the Holy Spirit was prompting and causing him to write it. In this giving context, Paul had just urged the Corinthians to abound in the grace of giving, then in verse 8 he says he speaks not by commandment, but by occasion of the forwardness or zealousness of others, and to prove the sincerity of their love.

2 Corinthians 8:8

I speak not by commandment, but by occasion of the forwardness of others, and to prove the sincerity of your love.

If Paul says he is not speaking by commandment, why is it still God's word?

Paul sometimes writes that he is not speaking by commandment, meaning the Lord did not directly tell him to give that instruction. Yet once it is placed in the written Word, it becomes inspired Scripture. The Holy Spirit prompted and caused Paul to write it, so it remains the Word of God.