Tafsir of Al-Mu'minoon 23:72

أم تسٲلهم خرجا

Or is it that you ask them for some Kharj, Al-Hasan said, "A reward.'' Qatadah said, "Some payment.''

فخراج ربك خير

But the recompense of your Lord is better, means, you are not asking for any wages or payment or anything for calling them to right guidance, rather you are hoping for a great reward from Allah, as He says:

قل ما سٲلتكم من أجر فهو لكم إن أجرى إﻻ على الله

Say: "Whatever wage I might have asked of you is yours. My wage is from Allah only.'' (34:47)

قل ما أسلكم عليه من أجر وما أنا من المتكلفين

Say: "No wage do I ask of you for this, nor am I one of the pretenders.'' (38:86)

قل ﻻ أسلكم عليه أجرا إﻻ المودة فى القربى

Say: "No reward do I ask of you for this except to be kind to me for my kinship with you.'' (42:23)

وجاء من أقصى المدينة رجل يسعى قال يقوم اتبعوا المرسلين اتبعوا من ﻻ يسلكم أجرا

And there came a man running from the farthest part of the town. He said: "O my people! Obey the Messengers. Obey those who ask no wages of you, and who are rightly guided.'' (35:20-21)

وهو خير الرازقين

and He is the Best of those who give sustenance

وإنك لتدعوهم إلى صراط مستقيم