A.T. Robertson Commentary John 4:51

"And as he was now going down, his servants met him, saying, that his son lived." — John 4:51 (ASV)

As he was now going down (ηδη αυτου καταβαινοντος). Genitive absolute in-spite of the fact that αυτω (associative instrumental case with υπηντησαν aorist active indicative of υπανταω) is near.

That his son lived (οτ ο παις αυτου ζη). Present active indicative preserved in indirect discourse (cf. the words of Jesus in verse 50). Note παις here (only example in John), υιος in 50, παιδιον (diminutive of tenderness) in 49.