[1]

On the Day of Reckoning, only the wealth spent on good deeds will be beneficial and similarly, only pious friends will benefit a person. Intercession is exclusive to the Muslims with the permission of Allah Almighty.

[2]

‘ظلم’ (injustice or oppression) literally means “to put something in its wrongful place.” Disbelievers adopting disbelief instead of faith, sin instead of obedience, and ungratefulness instead of gratitude are injustices. Since the worst type of injustice is described in this verse, the disbelievers are branded oppressors.