Yāmuk or Yòtmuk (peak of mouth) or Yamaka (the Book of Pairs) is the name of the sixth book of the Abhidhamma Pitaka. The content describes Patthāna (a condition which is the source of phenomena) and consists of 24 conditions starting hetu paccayo (condition that fortifies its conditioned stage) and ending with avigata paccayo (condition of the conditioned stages before its ceases).