The commandment of the Sabbath is discussed in many places in the Bible. It is connected with creation and with the exit from Egypt. In the Pentateuch these events present two of its justifications. Also in the history of Jewish explanations, the subject of the Sabbath is extremely extensive. Both are the foundation for understanding the importance of the Christian Lord's day - Sunday. This is exactly what the author deals with in his master's thesis - what the day of the Lord should represent to today's christian. When examining the current situation, beliefs and life of many believers in the Catholic Church, we can quickly see the relevance of this issue. The author wants to show correct understanding through three parts of the master's degree; first, it is to identify the ten commandments of God in the biblical context. This is followed by a detailed exegetical analysis of the commandment and its interpretation. All this shows us the central place that the third commandment occupies within the Bible. In the last section, the author presents the Jewish view of the Sabbath. Presented is their celebration of every Saturday. In addition, it presents how is their thinking connected with the things they do and what leads them to their relationship to the Sabbath, which truly represents one of the most important things in their lives. According to these findings, the task ultimately touches upon the Christian understanding of the Lord's day - from the first Church to the popes of our time.