The Prophetic narration: “Come forward and follow me in leading you in prayer, and let those after you follow you. Some people continue to delay [from the first line] until Allaah would delay them”. What is the meaning of the people who delay, who are included in the threat? Are they those who do not attend the congregational prayer at all, or are they those who are in the mosque but they delay joining the congregation when the prayer is called, or does this mean something else?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

As-Suyooti when interpreting this narration reported by Muslim said: "This refers to them delaying from joining the first line.” This meaning is supported by another narration which reads: “Some people continue to delay from joining the first line until Allaah would delay them.” [Abu Daawood and Al-Bayhaqi] 

Allaah Knows best.