As I understand it, there are no Biblical references to the “mystery” of the Trinity, and most especially no mention of it by Jesus in the Gospels. It was a “doctrine” invented centuries later.
The term “Trinity” is NOT in the Bible.
However, if you want to debate the Biblical basis for the Blessed Trinity or deny 3 persons in One God, Father, Son, and Holy Spirit, you better start another thread.
Meanwhile, read Jn 15:26
To help increase your "understanding":
Mat 3:13 Then Jesus came from Galilee to the Jordan to John, to be baptized by him.
Mat 3:14 John would have prevented him, saying, “I need to be baptized by you, and do you come to me?”
Mat 3:15 But Jesus answered him, “Let it be so now, for thus it is fitting for us to fulfill all righteousness.” Then he consented.
Mat 3:16 And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him;
Mat 3:17 and behold, a voice from heaven said, “This is my beloved Son, with whom I am well pleased.”
Here you have the Father, Son, and Holy Spirit together in one place at one time. Each distinctly, individually seen. It was not invented, it is a reality.