Allah the Almighty says:
"O mankind, you are laboring toward your Lord with [great] exertion and will meet it. Then as for he who is given his record in his right hand, he will be judged an easy account."
"And he will return to his people in happiness."
"But as for he who is given his record behind his back, he will cry out for destruction and [will] enter to burn in a Blaze."
Ibn 'Atiyyah al-Andalusi, may Allah have mercy on him, said:
The meaning is:
You are a worker of either good or evil.
And you are, inevitably, journeying toward your Lord in this.
For time flies by with the life of a human being.
Indeed, throughout the duration of his life, he is in a swift journey toward his Lord.
This is a verse of admonition and reminder.
Meaning:
Be wary of this state.
And perform righteous deeds so that you may find them [waiting for you].
Qatadah said:
Whoever is able to ensure that his labor is in the obedience of Allah the Almighty, let him do so.