The Holy Spirit, first of all, is a person and is referred to as “He”.

He is the third head of the trinity, advocate (John 16:7), comforter (John 14:26), Spirit of truth (John 16:13), helper and teacher (John 14:26), the one to remind us of all things spoken by God (John 14:26), the benefactor of gifts (1 Corinthians 12), agent of salvation.  

So why would you want to grieve the Holy Spirit and what grieves Him?

We can see the answer in several scriptures:

1. Rebellion, “Yet they rebelled and grieved his Holy Spirit. So he turned and became their enemy and he himself fought against them. Isaiah 63:10; 

2. Blasphemying the Holy Spirit, “but whoever blasphemes against the Holy Spirit will never be forgiven; they are guilty of an eternal sin.” Mark 3:29

3. Sinning willfully, “For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins,” Hebrews 10:26

4. Not glorifying God, “Of how much worse punishment, do you suppose, will he be thought worthy who has trampled the Son of God underfoot, counted the blood of the covenant by which he was sanctified a common thing, and insulted the Spirit of grace?” Hebrews 10:29