Is it permissible for one traveling for work and training in a foreign country, where it is difficult to determine prayer times, to shorten and combine prayers?

If a traveler intends to reside in a country for four days or more, he must perform the prayer in full, and it is not permissible for him to shorten or combine prayers. Prayer must be performed at its legally prescribed times, and it is not permissible to offer it early or delay it except for a legitimate excuse, as Allah Almighty says: "Indeed, prayer has been decreed upon the believers a prescribed time." One can rely on trusted calendars or contact Islamic centers to determine the times.