What is the permissible rest time during work in a marble factory so that it is not considered a dereliction of duty, and is it better to pray in congregation with the workers at their workplace or to pray alone in the mosque, and if a congregation is found in the mosque, then with which of the two congregations should one pray?

The benefit of a private employee is owned solely by the employer. The employee is not permitted to spend any part of the hired time on anything other than work, except for what is legally exempted, such as performing the obligatory prayers with their purifications and regular Sunnah without prolonging them, attending to personal needs, and eating in the shortest possible time. This also applies to what was stipulated in the contract or what the employee was granted permission for.

Taking breaks during work hours is not permissible except with the employer's permission. The employee must perform congregational prayers because they are obligatory according to the preponderant opinion, and congregational prayer in the mosque is better than praying outside of it.