It’s a very rare source of the scientific research in history that prove a promise that some people made for each other. It has got more importance if this is an oath of some roommates. Five students in Debrecen, who have lived their lives in the same dormitory room in the István Tisza Internate for years made a promise to each other in December 15, 1925. In writing they vowed that they will meet in Budapest in the Hotel Gellért on the day of Pentecost 6 years later. The text of the oath is an exact reflection of the age and of the „neo-baroque” society of the twenties. We don’t know that the meeting in 1931 could be realized or not, but we can suppose that could be, based on the strong friendship of the roommates. This strange oath is a very rare and valuable source of the students’ life between the two Wold Wars.