John 7:3

The desirableness of doing so is urged by His brothers. εἶπον … τῷ κόσμῳ. The reason they advanced was “that Thy disciples also may see Thy works which Thou doest”. καὶ οἱ μαθηταί σου seems to imply that since the Feeding of the Five Thousand in April, Jesus had been living in comparative retirement, perhaps at Nazareth. At Jerusalem, all who were attached to Him would be found at the Feast; and the brothers recognise that He would then have an opportunity of putting His claims to the proof. “No one,” they say, “who seeks public recognition confines his activities to a hidden and private corner.” ἐν παρρησίᾳ, as in John 11:54, means “openly” or “in public,” and is in direct contrast to ἐν κρυπτῷ. Having laid down the general law, they then apply it to Him, “if (or ‘since,' not expressing doubt) Thou doest these things, show Thyself to the world”. Lücke, following Euthymius, thinks doubt is implied in εἰ; but this implies an ignorance on the part of the brothers which is inconceivable.