I did know thee in the wilderness. The pronoun at the beginning of the verse is emphatic: As for me; or, I it was that knew thee. The meaning of the sentiment is: I acknowledged thee with kindness, with paternal care and kind providence watching over thee.
"Thou shouldest gratefully acknowledge me," is the comment of Kimchi, "because I knew thee in the wilderness, and cared for thy necessity in the wilderness, in which there were no means of livelihood."
In the land of great drought. The root of the word תַּלְאוּבֹת is לאב, unused in Hebrew, but signifying, in Arabic, "to burn, dry, be dry," akin to לָחַב. Aben Ezra correctly explains it to be "a dry and thirsty laud, and so in the Arabic language; and (that it is so called) on account of all hardships being in it, is the allegorical explanation and not the literal sense."
Instead of a lengthened enumeration of all God's loving-kindnesses to Israel at the Exodus and during the desert wanderings, the prophet sums up all in the expressive, "the Lord thy God from the land of Egypt;" and "I it was that did know thee in the wilderness."
It is as though he had said, "I pitied thee in the bondage and among the brick-kilns of Egypt; I brought thee forth with a strong hand and outstretched arm; I led thee through the wilderness; I relieved thee in thy straits; I gave thee bread from heaven to satisfy thy hunger, and water from the rock to quench thy thirst; I defended thee from enemies; nor did I relax my care till I gave thee the goodly laud of promise."