Knowledge of the Trinity is based on and rooted in scripture.
Absolutely not. Worship of the Holy Trinity (which is what I wrote; "knowledge" is not worship...you can know a lot of things without engaging in worship of those things) is based in the revelation of God Himself, not on the words of any book. We worship God (Father, Son, and Holy Spirit) according to how He has revealed Himself to us, not out of fidelity to the written text of a book, even a book that we very highly and very rightly venerate greatly for the truth and guidance contained therein.
In every morning hour of the Agpeya (Coptic daily prayer book akin to the Byzantine Horologion or the Latin Hours), we pray the following, which appears in modern printed copies of the book in English under the heading "The Faith of the Church":
One is God the Father of everyone.
One is His Son, Jesus Christ the Word, Who took flesh and died; and rose from the dead on the third day, and raised us with Him.
One is the Holy Spirit, the Comforter, one in His Hypostasis, proceeding from the Father, purifying the whole creation, and
teaching us to worship the Holy Trinity, one in divinity and one in essence. We praise Him and bless Him forever. Amen.
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By the bolded portion, we recognize that it is GOD Who teaches us to worship the Holy Trinity. Our God is not a book. Jesus Christ is the Word made
flesh,
not the Word made
text.
I don't know what that means.
I meant by that to maintain a distinction between what you asked for (a practice that is apostolic in vintage but not mentioned in the scriptures) and what can be argued for by the common reading of passages that are said to point to that thing. In other words: Yes, we can agree that Christians can and do find support for the worship of the Holy Trinity in the scriptures, but we should still recognize that we don't find explicit
report of it in them (i.e., there's no verse where we read "And St. Peter worshipped the Holy Trinity" in a manner analogous to what many people demand to substantiate things that they
don't agree with that other Christians do).