Sal?t with the congregation in the mosque, the Salaf used to perform the compulsory Sal?t followed by many N?filah [optional] Salaw?t in order to gain a reward equal to that granted for doing Sal?t with the congregation in the mosque. (1)
(6) The reason behind doing a second congregation is the slackness and laziness to attend the first congregation which is something detested, so pay heed to this.
(7) In addition to that, the prophet ( - صلى الله عليه وسلم -) never ordered muslims to conduct more than one congregation in Al-Khawf [fear] Sal?t and there was no proof that there used to be another congregation after his ( - صلى الله عليه وسلم -) and those who missed it used to perform the Sal?t individually or in a congregation at home -as was previously mentioned.
(8) A muslim who misses the congregation -due to a legal excuse- at the mosque, may then do his Sal?t alone and would be granted a reward equal to that given to him as if he did it with the congregation.
The prophet ( - صلى الله عليه وسلم -) said: ‘Whoever performs perfect Wud?’ then walks to [the mosque to do] the Sal?t, All?h ( - عز وجل -) will record a reward for him whenever he steps with his right foot, and will wipe out a sin whenever he steps with his left. Accordingly; one would get a reward in proportion to the steps he takes to the mosque, be it near of far. And when one attends the mosque and joins the congregation in Sal?t, his sins will be forgiven. If one misses a part of the Sal?t with the congregation, then joins the congregation with what is left and completes what he missed, he would also get a full reward. In case one reaches the mosque and finds that the congregation had already finished the Sal?t and then performs his Sal?t alone perfectly, he would also receive the full reward’. (2)
(1) See: “Siyar A‘lamun Nubal?’ “(vol. 12 / p.495) and (vol. 11 / pp.443 - 4).
(2) Narrated by Ab? D?w?d in “As-Sunnan” (vol. 1 / p.154) (no.563) and so did Al-Baihaqi in “As-Sunnan Al-Kubr?” (vol. 3 / p.69). The had?th is authentic and it is reported in “Sah?h Al-J?mi‘ As-Sagh?r” (no.440).