Parallel
John 11:13
Patriarchal Greek New Testament (1904) · Berean Standard Bible
εἰρήκει δὲ ὁ Ἰησοῦς περὶ τοῦ θανάτου αὐτοῦ· ἐκεῖνοι δὲ ἔδοξαν ὅτι περὶ τῆς κοιμήσεως τοῦ ὕπνου λέγει.
They thought that Jesus was talking about actual sleep, but He was speaking about the death of Lazarus.