Jamieson, Fausset and Brown on John 1:48

48. Whence knowest thou me--conscious that his very heart had been read, and at this critical moment more than ever before.

Before Philip called thee--showing He knew all that passed between Philip and him at a distance.

when ... under the fig tree, &c.--where retirement for meditation and prayer was not uncommon [Lightfoot]. Thither, probably--hearing that his master's Master had at length appeared, and heaving with mingled eagerness to behold Him and dread of deception--he had retired to pour out his guileless heart for light and guidance, ending with such a prayer as this, "Show me a token for good!" (See on Lu 2:8). Now he has it, "Thou guileless one, that fig tree scene, with all its heaving anxieties, deep pleadings and tremulous hopes--I saw it all." The first words of Jesus had astonished, but this quite overpowered and won him.