Q source
The Q source (also called the Sayings Gospel, Q Gospel, Q document(s), or Q; from German: Quelle, meaning "source") is a hypothesized written collection of primarily Jesus' sayings (λόγια, logia). Q is part of the common material found in the Gospels of Matthew and Luke but not in the Gospel of Mark. According to this hypothesis, this material was drawn from the early Church's oral gospel traditions.
Q had been hypothesized by 1900 alongside Marcan priority. Some scholars have postulated that Q is actually a plurality of sources, some written and some oral. Others have attempted to determine the stages in which Q was composed. Despite the two-source hypothesis enjoying wide support, Q's existence has been increasingly questioned by alternative theories such as the Farrer and Matthean Posteriority hypotheses.