Their diligence in the preaching and disciple - making work is well - documented in the Bible book of Acts.
وَيَتَضَمَّنُ سِفْرُ ٱلْأَعْمَالِ سِجِلًّا مُفَصَّلًا عَنِ ٱجْتِهَادِهِمْ فِي ٱلْبِشَارَةِ وَٱلتَّلْمَذَةِ .‏