Jesus and His Apostles were fluent in Scripture ... Jesus at this point does not confer authority to St. Peter, so his later denial of Christ does not render it void. Christ actually prays ...

In any case, a person who wants to deny the teaching about abortion would ... 20:13, Deut. 5:17) and Christ re-affirms it (Mt. 19:18 — notice that He mentions this commandment first.) ...