John 5:1

Some time later Jesus returned to Jerusalem to celebrate one of the Jewish feasts and to use that occasion to minister. John did not specify which feast it was. Elsewhere in his Gospel when John identified the feast in view he did so because the events and teaching that followed had relevance to that particular feast (cf. John 2:13; John 6:4; John 7:2; John 10:22; John 11:55). Here they did not. Consequently the identity of the feast is unimportant for the interpretation of the text. Hoehner favored one of the three pilgrim feasts that the Mosaic Law required Jewish males to attend: Passover, Pentecost, or Tabernacles. He preferred the last of these though conceded that certain identification is probably impossible. [Note: Hoehner, pp. 58-59.] John probably just mentioned the feast to explain Jesus’ return to and presence in Jerusalem.