What is the ruling on the Dhuhr prayer if I wake up in a state of major ritual impurity (janābah) and there is no place to perform ghusl at work, and I cannot return home until just before Maghrib? Is it permissible to perform tayammum and pray, or is it obligatory to go to a nearby brother's house to perform ghusl? And is it obligatory to repeat the Dhuhr prayer after performing ghusl?

Whoever finds themselves without ritual purity when prayer time enters must purify themselves with water if it is available, or search for it if they strongly believe it exists. If they perform tayammum (definition) and pray without searching for water, while believing it exists, they must repeat the prayer.

However, if prayer time enters and they do not find water or are unable to purify themselves, they should perform tayammum and pray at the beginning of the time without delay. They are not required to repeat the prayer, even if they know they will find water later.

Based on this, if the enquirer can purify themselves at their brother's house, they are obligated to do so, and it is not permissible for them to perform tayammum or delay the prayer. But if they cannot purify themselves at their brother's house, they should perform tayammum and pray at the beginning of the time, and they are not required to repeat the prayer.