Albert Barnes on John 1:47

An Israelite indeed. One who is really an Israelite--not by birth only, but one worthy of the name. One who possesses the spirit, the piety, and the integrity which become a man who is really a Jew, who fears God and obeys his law. Comp. Rom 9:6, 2:28,29.

No guile. No deceit, no fraud, no hypocrisy. He is really what he professes to be--a Jew, a descendant of the patriarch Jacob, fearing and serving God. He makes no profession which he does not live up to. He does not say that Nathanael was without guilt or sin, but that he had no disguise, no trick, no deceit--he was sincere and upright. This was a most honourable testimony. How happy would it be if he, who knows the hearts of all as he did that of Nathanael, could bear the same testimony of all who profess the religion of the gospel!

(n) "Behold" Ps 32:2, Rom 2:28,29