The principle of reciprocity is universal in human society and an important value of Philippine cultures. The description of the marriage negotiations of the Sama Dilaut of Sulu in Southwestern Philippines is an illustration of one reciprocal function and its stabilizing effect on a contract which is potentially unstable. Appendices to this article include: (1) Key to pronunciation to phonemes of Samal language, (2) Kinship Chart of Sama informant, (3) a text that reflects adaptation of the Arabic to Samal phonology, and (4) exceptions to Samal marriage procedure.