Genesis 13:2

And Abram had become very strong in cattle, in silver, and in gold.

ואברם כבד מאד במקנה, this is why he had to travel slowly, even though he wanted to return quickly to the site of the altar where he wanted to continue his preaching as he had done before the famine.

ואברם כבד מאד, he was very wealthy both in herds and flocks, as well as in other possessions, all chattels. The attribute כבד for great wealth has been chosen since, seeing it consists of chattels, it is “weighty” in the truest sense of the words. Similar literary formulations are found in Isaiah 1,30 כאלה נובלת עליה, “as a terebinth wilted of its leaf,” the prophet uses the word עלה, leaf, as something descriptive of a small tree like the terebinth whose leaf patterns account for its character. Its leaves make it such an outstanding tree. Similarly, the expression קרועי בגדים. In Samuel II 13,31 “with their clothes rent,” or מגולחי זקן, “shorn of beard,” in Jeremiah 41,5. The adjectives used fit the noun they describe, so here too the adjective כבד “heavy,” fits such metals as silver and gold, so that wealth may be appropriately described in such terms. [The author explains why a simple term such as עשיר, “rich,” was not used instead of the adjective כבד, literally “heavy.” Ed.]