يَقُومُ (stand before): expresses the panic.  Everyone will standup frightened from the horror of this situation; when all mankind will stand before the Lord (swt) who created from nothing, provided sustenance from nothing and took charge of care and raising. He (swt) is the Most Gracious and Most Merciful who has pity on his slaves for they are his creation and He is the most Merciful towards them.