Like a crane... — The three birds — strictly, the “swift,” the “crane,” the “dove” — each with its special note of lamentation, represent, as it were, the cries of pain and the low suppressed wail of the sufferer. The three appear again together in Jeremiah 8:7.
Undertake for me — i.e., as in Genesis 43:9; Genesis 44:32; Job 17:3, Be surety for me. The idea is that of Death, who, yet in another sense, is but the minister of Jehovah, as being the creditor pressing for immediate payment. The words involve (as Cheyne points out) something like an appeal to the judge, who is also the accuser, to be bail for the accused.