What is the earliest extrabiblical teaching of baptism using a trinitarian formula?

[Oneness Pentecostals and others](https://christianity.stackexchange.com/q/33218/21576) who hold to "Jesus-name" (or "Jesus-only") baptism maintain that the trinitarian formula used by Nicene Christians and others is based on a misunderstanding of Matthew 28:19 and a failure to recognize that all recorded baptisms in the New Testament were done in the name of Jesus only. The argument goes something like this: - [Matthew 28:19](https://www.biblegateway.com/passage/?search=matthew+28%3A19&version=ESV) refers to a single "name" of the Father, Son, and Holy Spirit, and that "name" is *Jesus*. - Baptisms and baptismal commands described in [Acts 2:38](https://www.biblegateway.com/passage/?search=acts+2%3A38&version=ESV) , [8:16](https://www.biblegateway.com/passage/?search=acts+8%3A16&version=ESV) , [10:48](https://www.biblegateway.com/passage/?search=acts+10%3A48&version=ESV) , [19:5](https://www.biblegateway.com/passage/?search=acts+19%3A5&version=ESV) , and [22:16](https://www.biblegateway.com/passage/?search=acts+22%3A16&version=ESV) all invoke the name of Jesus, with no indication of a trinitarian formula. To me the second point in particular is not easily dismissed. I'm thus interested in the history of the trinitarian baptismal formula. What is the earliest extrabiblical teaching on baptism that contradicts "Jesus-name" baptism and calls for a trinitarian (three-part) baptismal formula? ---------- To be clear, the word *trinitarian* here does not indicate a belief in *Nicene trinitarianism*: it simply refers to the three-part nature of the baptismal formula: Father, Son, Holy Spirit. So a church father whose views do not neatly coincide with Nicaea's could still employ a "trinitarian baptismal formula."