These two prayers are the most burdensome of all prayers for the hypocrites. If you knew what they contain, you would come to them, even if you had to crawl on your knees

The Prophet (may Allah's peace and blessings be upon him) offered the Fajr prayer one day and then asked: Is so-and-so attending this prayer of ours? The Companions replied: No! Then he said: Is so-and-so present? Another person. They said: No!

So, the Prophet (may Allah's peace and blessings be upon him) said: Indeed, the Fajr and ‘Ishā’ prayers are the most burdensome of all prayers for the hypocrites, as people are mostly lazy at their time and they have little chance of Riyā’ (show-off), for they are not seen in darkness.

If you, O believers, knew the additional reward and recompense that results from the Fajr and ‘Ishā’ prayers - as the amount of reward depends on the amount of difficulty - you would come to them, even if you had to crawl on your hands and knees. The first row, in terms of their closeness to the Imām, is like the row of angels in terms of their closeness to Allah Almighty. If the believers knew the merit of the first row, they would race to join it.

And indeed, a man's prayer with another man brings more reward and impact than his prayer alone, and his prayer with two men is better than his prayer with one man. A prayer attended by a lot of worshippers is more rewarding and pleasing to Allah.