Genesis 1:26
New International Version (NIV)
Then God said, “Let us make mankind in our image, in our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.”
Ahmed already addressed this when describing the royal plural.
Genesis 1:26
New International Version (NIV)Then God said, “Let 
us make mankind in 
our image, in 
our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.”
The very word Elohim (אֱלֹהִ֔ים) used of the true God in Genesis 1:26 is a grammatically singular or plural noun for "god" or "gods" in both modern and ancient Hebrew language.
So not only does Genesis 1:26 offer support for the Trinity, but also the name Elohim itself in its singularity offers support for One True God, yet at the same time in its plurality offers support for three persons in the one God: Father, Son and Holy Spirit, who are mentioned later in the Bible:
Matthew 28:19Therefore go and make disciples of all nations, baptizing them in the name of the 
Father and of the 
Son and of the 
Holy SpiritJohn 1:1-31 In the beginning was the Word, and the Word was with God, and 
the Word was God. 
2 He was with God in the beginning. 
3 
Through him all things were made; without him nothing was made that has been made.
John 1:9-149 The true light that gives light to everyone was coming into the world. 
10 He was in the world, and
 though the world was made through him, the world did not recognize him. 
11 He came to that which was his own, but his own did not receive him. 
12 Yet to all who did receive him, to those who believed in his name, he gave the right to become children of God— 
13 children born not of natural descent, nor of human decision or a husband’s will, but born of God.
14 
The Word became flesh and made his dwelling among us. We have seen his glory, the glory of 
the one and only Son, who came from the Father, full of grace and truth.