Acts 1:16 Men and brethren, this scripture must needs have been fulfilled, which the Holy Ghost by the mouth of David spake before concerning Judas, which was guide to them that took Jesus.

Peter claims that Psalms 41:9 is a prophecy of Judas betraying Jesus but the Psalm is only about David's current plight without any prophetic or future aspect.

Ps 41:9 Yea, mine own familiar friend, in whom I trusted, which did eat of my bread, hath lifted up his heel against me.