Jeremiah 26:15

26:15 But you should take careful note of this: If you put me to death, you will bring on yourselves and this city and those who live in it the guilt of murdering an innocent man. For the Lord has sent me to speak all this where you can hear it. That is the truth!” ¹ 

Jeremiah 40:15

40:15 Then Johanan son of Kareah spoke privately to Gedaliah there at Mizpah, “Let me go and kill Ishmael the son of Nethaniah before anyone knows about it. Otherwise he will kill you ²  and all the Judeans who have rallied around you will be scattered. Then what remains of Judah will disappear.”

[26:15]  ¹ tn Heb “For in truth the Lord has sent me to you to speak in your ears all these words/things.”

[40:15]  ² tn Heb “Why should he kill you?” However, this is one of those cases listed in BDB 554 s.v. מָה 4.d(b) where it introduces a question introducing rhetorically the reason why something should not be done. In cases like this BDB notes that it approximates the meaning “lest” and is translated in Greek by μήποτε (mhpote) or μή (mh) as the Greek version does here. Hence it is separated from the preceding and translated “otherwise” for the sake of English style.