Acts 21:26

Purifying himself [α γ ν ι σ θ ε ι ς]. See on 1 Peter 1:22; James 4:8. Declaring [δ ι α γ γ ε λ λ ω ν]. To the priests who directed the sacrifices and pronounced release from the vow.

Fulfillment - until, etc. There is some dispute and confusion here as to the precise meaning. The general sense is that, having entered the temple toward the close of the period required for the fulfillment of these men's vow he gave notice that the vowed number of Nazarite days had expired, after which only the concluding offering was required.