σύ,
pron. of 2nd of person(s),
thou, you, genitive, σοῦ, dative, σοί, accusative, σέ, pl., ὑμεῖς, -ῶν, -ῖν, -ᾶς (enclitic in oblique cases sing., except after prep. (BL, §48, 3), though πρὸς σέ occurs in Mat.25:39). Nom. for emphasis or contrast: Jhn.1:30, 4:10, 5:33, 39, 44, Act.4:7, Eph.5:32; so also perhaps σὺ εἶπας, Mat.26:64, al. (M, Pr., 86); before voc., Mat.2:6, Luk.1:76, Jhn.17:5, al.; sometimes without emphasis (M, Pr., 85f.), as also in cl., but esp. as rendering of Heb. phrase, e.g. υἱός μου εἶ σύ (בְּנִי־אַתָּה, Psa.2:7), Act.13:33. The genitive (σοῦ, ὑμῶν) is sometimes placed bef. the noun: Luk.7:48, 12:30, al.; so also the enclitic σοῦ, Mat.9:6; on τί ἐμοὶ κ. σοί, see: ἐγώ.
(AS)