“The internal witness is one alone; namely of the holy Ghost inwardly speaking to our heart, and persuading us that those writings are inspired of God, and sealing them up in our hearts, Eph. 1:13; 1 John 2:20, 27, Ye have an anointment of the Lord, and this anointment teaching you all things. For whosoever are led by the Spirit of God, can easily discern his power speaking in the Scriptures….And this testimony properly maketh for our confirmation, and this alone doth satisfy us, being known of them alone that are converted unto Christ, which doth evermore agree with the Scripture, without which the testimony of the Church can be no weight with us. For as none but God alone is a fit witness to testify of himself in his word, even so the word never findeth credit in our hearts, till such time as it be sealed up unto us by the inward testimony of the Spirit.”
William Bucanus, Body of Divinity, 42, 45-46.