Grief to my sorrow - Baruch's sorrow is caused by the sinfulness of the Jewish nation, to which God adds grief by showing how severely it will be punished.
I fainted in - Or, "am weary with" Psalm 6:6.

Thou didst say, Wo is me now! - All that were the enemies of Jeremiah became his enemies too; and he needed these promises of support.
The Lord hath added grief to my sorrow - He had mourned for the desolations that were coming on his country, and now he mourns for the dangers to which he feels his own life exposed; for we find, from Jeremiah 36:26, that the king had given commandment to take both Baruch and Jeremiah, in order that they might be put to death at the instance of his nobles.

Thou didst say, Woe is me now! for the LORD hath added grief to my sorrow; I (c) fainted in my sighing, and I find no rest.
(c) Baruch moved with an inconsiderate zeal for Jeremiah's imprisonment, but chiefly for the destruction of the people and the temple makes this lamentation, as in (Psalm 6:6).

Thou didst say, woe is me now!.... What will become of me? I am ruined and undone; this he said in his heart, if not with his lips, perhaps both ways; and when the king gave orders for the apprehending of him and the prophet, being provoked at the roll which he had wrote and read, Jeremiah 36:26;
for the Lord hath added grief to my sorrow; caused him grief upon grief, sorrow upon sorrow, an abundance of it; for there was a variety of things which occasioned grief and sorrow; the trouble of his office, as secretary to the prophet; the reproach east upon him by the people for it; the grievous things contained in the prophecies he transcribed, concerning the ruin of his people and nation; the king's displeasure at the roll, and his burning it; to which was added the danger he was exposed unto for writing it; and especially, as he might apprehend, for writing it over again, after it was burnt; to which were annexed new threatenings, and such as personally concerned the king;
I fainted in my sighing; or "with" it; he sighed and groaned at what he saw coming upon his country, and particularly upon himself; it quite overcame his spirits; he sunk and swooned away: or "I laboured in my sighing" (n); amidst his sighs and groans, he prayed to the Lord, and laboured in prayer, that he might be delivered from the evils he feared were coming upon him:
and I find no rest; from his grief, sorrow, and sighing; no cessation of that; no serenity and composure of mind; no answer of prayer from God. The Targum is,
"and I found not prophecy.''
And the Jewish commentators, as Jarchi, Kimchi, Abarbinel, and Abendana, from the ancient Midrashes, interpret this grief of Baruch to be on account of his not having the gift of prophecy bestowed on him, which he expected by being a servant of the prophet (o); and represent him as saying, Joshua ministered to Moses, and the Holy Spirit dwelled upon him; Elisha ministered to Elijah, and the Holy Spirit rested upon him; how different am I from all the disciples of the prophets! "woe is me now!" &c.
(n) "in gemitu meo", V. L. Pagninus, Montanus, Vatanblus, "in suspirio meo", Cocceius, Schmidt. (o) Vid. Maimon. Moreh Nevochim, par. 2. c. 32. p. 286.

Thou didst say, &c.--Jeremiah does not spare his disciple, but unveils his fault, namely, fear for his life by reason of the suspicions which he incurred in the eyes of his countrymen (compare Jeremiah 36:17), as if he was in sympathy with the Chaldeans (Jeremiah 43:3), and instigator of Jeremiah; also ingratitude in speaking of his "grief," &c., whereas he ought to deem himself highly blessed in being employed by God to record Jeremiah's prophecies.
added--rescued from the peril of my first writing (Jeremiah 36:26). I am again involved in a similar peril. He upbraids God as dealing harshly with him.
I fainted--rather, "I am weary."
no rest--no quiet resting-place.

I find no rest - Upon Baruch's reading the prophecies both he and Jeremiah were advised to hide themselves. This probably disturbed Baruch, and made him lament his condition.