C. F. Keil and Franz Delitzsch on 2 Kings 21:16

2Ki 21:16

Manasseh also sinned grievously by shedding innocent blood till Jerusalem was quite filled with it. לפה פּה, from one edge to the other, see at 2Ki 10:21. This statement has been paraphrased by Josephus thus (Ant. x. 3, 1): Manasseh slew πάντας ὁμῶς τοὺς δικαίους τοὺς ἐν τοῖς Ἑεβραίοις, and did not spare even the prophets, with the additional clause, which exaggerates the thing: καὶ τούτων δέ τινας καθ ̓ ἡμέραν ἀπέσφαξε, ὥστε αἵματι ῥεῖσθαι τὰ Ἱεροσόλυμα.The widespread Jewish and Christian legend, that Manasseh put to death the prophet Isaiah, and indeed had him sawn in sunder, to which there is an allusion in Heb 11:37, also belongs here. (See Delitzsch, Comm. on Isaiah, p. 5.)