The Syro-Roman Lawbook, written in Greek and translated to Syriac at the end of the fifth century, is perceived as one of the early representatives of Roman influence on Syriac Christianity. However, tracing the roots of two customs documented in this composition shows earlier influence of Roman law in the Christian east. According to the Syro-Roman Lawbook, a kiss and earnest are both given during the process of betrothal in order to strengthen its validity. Even though both customs are well attested in Roman law and Latin Christian sources, they are also found in non-legal Greek writings as early as the third century, and non-legal Syriac writings as early as the fourth century. These findings show that the influence of Roman law on the Christian east in general and the Syrian east in particular, is not only earlier than thought but also more profound. The non-legal sources show that these legislations were neither introduced to Syriac Christians through the Syro-Roman Lawbook, nor imposed as new legislations, but rather were known and practiced by the fourth century if not earlier.