﴿ أَمْ تَسْـَٔلُهُمْ أَجْرًۭا فَهُم مِّن مَّغْرَمٍۢ مُّثْقَلُونَ ﴾

“Or is it that [they fear lest] thou ask them for a reward, [O Prophet,] so that they would be burdened with debt [if they listened to thee]?”

Or are you asking them a fee in return for delivering the Message so that they are weighed down with debt? so that they are weighed down with what they will have to give you and that is why they do not believe.