Seeing ye have purified (ηγνικοτες). Perfect active participle of αγνιζω, old verb from αγνος (pure), here with ψυχας (souls), with καρδιας (hearts) in James 4:8 as in 1. John 3:3 of moral cleansing also. See the ceremonial sense of the word as in LXX in John 11:55; Acts 21:24; Acts 21:26; Acts 24:18.

In your obedience (εν τη υπακοη). With repetition of the idea in 1. Peter 1:2; 1. Peter 1:14 (children of obedience).

To the truth (της αλεθειας). Objective genitive with which compare John 17:17; John 17:19 about sanctification in the truth and 2. Thessalonians 2:12 about believing the truth. There is cleansing power in the truth of God in Christ.

Unfeigned (ανυποκριτον). Late and rare double compound, here alone in Peter, but see James 3:17; 2. Corinthians 6:6, etc. No other kind of φιλαδελφια (brotherly love) is worth having (1. Thessalonians 4:9; Hebrews 13:1; 2. Peter 1:7).

From the heart fervently (εκ καρδιας εκτενως). Late adverb (in inscriptions, Polybius, LXX). The adjective εκτενης is more common (1. Peter 4:8).