The Son doth not say, The Father is in Me, and I in Him, in the sense in which men who think and act aright may say the like; meaning that they partake of God’s grace, and are enlightened by His Spirit. The Only-begotten Son of God is in the Father, and the Father in Him, as an equal in an equal.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Tract. xlviii. 10