After His commandments (κατὰ τὰς ἐντολὰς αὐτοῦ)
For walk, with κατά after, according to, see Mar 7:5; Rom 8:4; Rom 14:15; 1Co 3:3; 2Co 10:2. Very often with ἐν in. See Joh 8:12; Joh 11:9, Joh 11:10; 2Co 4:2; 1Jo 1:7, 1Jo 1:10. Both constructions are found 2Co 10:2, 2Co 10:3.