What is the purpose of there being rewards in heaven?

This article has been translated into the following languages:

العربية Български 中文 中國話 Deutsch Español فارسی Français Ελληνικά हिन्दी Hrvatski Bahasa Indonesia Italiano 日本語 Kiswahili 한국어 Magyar Polski Português Română Русский සිංහල Srpski Tagalog ไทย Українська اردو Tiếng Việt