John Lightfoot on John 1:47

[An Israelite indeed.] Compare it with Isaiah 63:8. "I saw thee (saith Christ) when thou wert under the fig tree." What doing there? Doubtless not sleeping, or idling away his time, much less doing any ill thing. This would not have deserved so remarkable an encomium as Christ gave him. We may therefore suppose him, in that recess under the fig tree, as having sequestered himself from the view of men, either for prayer, meditation, reading, or some such religious performance; and so indeed from the view of men, that he must needs acknowledge Jesus for the Messiah for that very reason, that, when no mortal eye could see, he saw and knew that he was there. Our Saviour, therefore, calls him an "Israelite indeed, in whom there was no guile," because he sought out that retirement to pray, so different from the usual craft and hypocrisy of that nation, that were wont to pray publicly, and in the streets, that they might be seen of men.

And here Christ gathered to himself five disciples, viz., Andrew, Peter, Philip, Nathanael (who seems to be the same with Bartholomew), and another, whose name is not mentioned, verse 35, 40; whom, by comparing John 21:2, we may conjecture to have been Thomas.