What is the ruling on combining the four prayers at the time of 'Isha' due to difficult working conditions that prevent purification and the unavailability of water or ablution facilities? Does wiping the penis on a wall suffice for istijmar? What is the ruling on the presence of fecal stains on underwear? And how does one pray when the direction of the Qibla is unknown?

Prayer is obligatory at its appointed time, and delaying it without a legitimate Shari excuse is not permissible. Severe sweating is not an excuse for combining prayers. Wiping the penis on a wall for istijmar is sufficient. If it is possible to carry water for ablution, then it is necessary; otherwise, tayammum (definition) is prescribed. The spots of feces must be washed from the garment, or it should be changed to a pure garment. If this is not possible, then pray in your current state. Diligence must be exercised in determining the Qibla (definition); if you err in your diligence, you are not required to repeat the prayer.