2 Samuel 10:3 And the princes of the children of Ammon said unto Hanun their lord, Thinkest thou that David doth honour thy father, that he hath sent comforters unto thee? hath not David rather sent his servants unto thee, to search the city, and to spy it out, and to overthrow it?
John 14:16
And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
Psalm 69:20 Reproach hath broken my heart; and I am full of heaviness: and I looked for some to take pity, but there was none; and for comforters, but I found none.
Genesis 2:18 The Lord God said, “It is not good for the man to be alone. I will make a helper suitable for him.”
19 Now the Lord God had formed out of the ground all the wild animals and all the birds in the sky. He brought them to the man to see what he would name them; and whatever the man called each living creature, that was its name. 20 So the man gave names to all the livestock, the birds in the sky and all the wild animals. But for Adam no suitable helper was found.
At first woman were considered as the comforters, and so the only one that Cain could of have been referring to is his wife.