The verb kul means to sustain, nourish, maintain, or contain. In its concrete sense it can mean to hold or contain (as a vessel holds water). In its more common figurative sense it means to provide for and sustain — to bear the weight of another's needs over time. It is used of God sustaining his servants, and of people bearing or enduring hardship.
Divine sustenance is central to the covenant relationship. God sustained Israel in the wilderness for forty years (Deuteronomy 8:4), and he sustains his servants in times of distress. The great question of Malachi 3:2 — 'Who can endure (kul) the day of his coming?' — points to God's overwhelming holiness, which no human can bear apart from his grace. Joseph sustained his father Jacob and brothers during the famine (Genesis 45:11; 50:21), foreshadowing how God provides through human instruments. Ultimately, God alone truly sustains all things (Colossians 1:17).