"Gen_1:26 Gen_3:22 Gen_11:7 Gen_20:13 Gen_31:7, Gen_31:53 Gen_35:7. "Deu_4:7 Deu_5:23; Jos_24:19 1Sa_4:8; 2Sa_7:23; "Psa_58:6; Isa_6:8; Jer_10:10, Jer_23:36. "See also Pro_9:10, Pro_30:3; Psa_149:2; Ecc_5:7, Ecc_12:1; Job_5:1; Isa_6:3, Isa_54:5, Isa_62:5; Hos_11:12, or Hos_12:1; Mal_1:6; Dan_5:18, Dan_5:20, and Dan_7:18, Dan_7:22." - Parkhurst.

The question of whether or not the concept of the Trinity or suggestion of God as Triune is in fact in the Bible is valid.  So far there is one witness to the concept of the Triune God, taking contextual and grammatical evidence as a whole along with the deductions of the rabbi cited above.  He is not alone among other Jews.  In fact there is specific evidence that is more obvious than the testimony of those who only consider the TaNaK as sacred scripture. The several citations comprise more than the three required witnesses to testify to the truthfulness of the factual state of a matter.

The Christophanies that occur in the Old Testament establish the known presence of Jesus as the LORD Sabaoth as He is referred to in the New Testament.  Therefore the presence of God the Father, God the Son, and God the Holy Spirit are referred to many times. For a fuller treatment of this aspect of the revelation of Jesus, follow this link to Christophany.

He said: They are indeed my people,

children who are not disloyal;

So he became their savior

in their every affliction.

It was not a messenger or an angel,

but he himself who saved them.

Because of his love and pity

he redeemed them himself,

Lifting them and carrying them

all the days of old.

But they rebelled, and grieved

his holy spirit;

So he turned on them like an enemy,

and fought against them.

Isaiah 63:8-10

"The Angel of His Presence" occurs here in parallel to pronouns referring to God Himself. This is the Angel of the Lord who acted on Israel’s behalf at the Exodus and other times and is considered to have been the preincarnate Christ (cf. Genesis 18:2, note; Exodus 14:19; 23:20–23; Joshua 5:13–15, note; Judges 13:18, note). Verses 8–10 refer to God as Father (v. 8), "Angel" (v. 9), and "Holy Spirit" (v. 10), a hint of the triune nature of God more fully presented in the New Testament (cf. Luke 3:22).

The first citation selected has the witness of the Prophet Isaiah who related in written record the testimony of the Father from the Holy Spirit about the Son.  It also happens that this is a prophecy fulfilled by Jesus.  No one in all of recorded history has fulfilled this prophecy except Jesus.

Here is my servant whom I uphold,

my chosen one with whom I am pleased,

Upon whom I have put my spirit;

he shall bring forth justice to the nations,

Not crying out, not shouting,

not making his voice heard in the street.

A bruised reed he shall not break,

and a smoldering wick he shall not quench,

Until he establishes justice on the earth;

the coastlands will wait for his teaching.

Isaiah 42:1-4

Come ye near unto me, hear ye this; I have not spoken in secret from the beginning; from the time that it was, there am I: and now the Lord GOD, and his Spirit, hath sent me.

Isaiah 48:16

This is obviously Jesus speaking as He was with the Father and the Holy Spirit at the beginning.

After Jesus was baptized, he came up from the water and behold, the heavens were opened (for him), and he saw the Spirit of God descending like a dove (and) coming upon him.

And a voice came from the heavens, saying, "This is my beloved Son, with whom I am well pleased."

Matthew 3:16-17

When they saw him, they worshiped, but they doubted.

Then Jesus approached and said to them, "All power in heaven and on earth has been given to me.

Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the holy Spirit,

teaching them to observe all that I have commanded you. And behold, I am with you always, until the end of the age."

Matthew 28:17-20

and the holy Spirit descended upon him in bodily form like a dove. And a voice came from heaven, "You are my beloved Son; with you I am well pleased."

Luke 3:22

Luke here indicates how the Holy Spirit becomes visible to both Jesus and John (Matthew 3:16; John 1:32). The import of this event is crucial in theology. This verse denies modalism, the heresy which construed the unity of God to be manifested in three different, momentary forms—Father, Son and Holy Spirit. The idea of God appearing sometimes as one and then as the other is proved to be unscriptural. Here there is simultaneously the appearance of Son and Holy Spirit. At the same time the voice of the Father is heard. Clearly, God is the triune God, eternally Father, Son and Holy Spirit (cf. I Peter 1:2). Luke quotes from Psalm 2:7 and Isaiah 42:1, which identify Jesus as the Son of God and the Suffering Servant. All three Persons of the Triunity are here together for the first time in the Gospel.

W. A. Criswell, Believer’s Study Bible [computer file], electronic ed. , Logos Library System, (Nashville: Thomas Nelson) 1997, ^©1991 by the Criswell Center for Biblical Studies.

In the first book, Theophilus, I dealt with all that Jesus did and taught

until the day he was taken up, after giving instructions through the holy Spirit to the apostles whom he had chosen.

He presented himself alive to them by many proofs after he had suffered, appearing to them during forty days and speaking about the kingdom of God.

While meeting with them, he enjoined them not to depart from Jerusalem, but to wait for "the promise of the Father about which you have heard me speak;

for John baptized with water, but in a few days you will be baptized with the holy Spirit."

Acts 1:1-5