Job 40:21

“He lieth under the shady trees, in the covert of the reed, and fens.] This may be thought to agree very well with the river horse, the inhabitant of the Nile, where reeds in great plenty grew, and adjoining to which were fenny and marshy places, and shady trees; and, as historians relate f1494, this creature takes its lodging among high reeds, and in shady places; yea, the reeds and sugar canes, and the leaves of the papyrus, are part of the food on which it lives; and hence the hunters of them sometimes cover their bait with a reed to take them; though it must be allowed that the elephant delights to be about rivers, and in clayey and fenny places f1495, and therefore Aelianus f1496 says it…”

“lieth--He leads an inactive life. shady trees--rather, "lotus bushes"; as Job 40:22 requires.”

“He lieth under the shady trees - Referring to his usually inactive and lazy life. He is disposed to lie down in the shade, and especially in the vegetable growth in marshy places on the banks of lakes and rivers, rather than to dwell in the open field or in the upland forest. This account agrees well with the habits of the hippopotamus. The word here and in Job 40:22 rendered “shady trees” (צאלים tse'eliym), is by Gesenius, Noyes, Prof. Lee, and Schultens, translated “lotus,” and “wild lotus.” The Vulgate, Syriac, Rosenmuller, Aben-Ezra, and others, render it “shady trees.” It occurs nowhere else in the Scriptures, and it is difficult, therefore, to determine its meaning. According to…”

“the reed: Isa 19:6, Isa 19:7, Isa 35:7 Job 40:22”