בראשית, פרק ל״ח, פסוק כ״ח

The moment of birth can sometimes bring rare and dramatic physical phenomena, creating confusion about the identity of the true firstborn. During a complex delivery of twins, a fleeting occurrence requires a midwife to act swiftly to establish the legal and spiritual status of the children. The primary approach among commentators is that as the birth progressed, one infant's hand emerged outside the womb. This was not a deliberate reach by the unborn child, but rather a factual consequence of the delivery process. The infant appeared ready to enter the world but failed to complete his exit, remaining unnamed at this stage simply because neither child had yet been given a name [אבן עזרא, ביאור יש״ר]. This unusual event was accompanied by a physical marvel in which both placentas opened simultaneously, sparking a struggle within the womb [אבן עזרא, מחוקקי יהודה].

Recognizing the highly unusual nature of the situation, the midwife quickly grasped the exposed hand before it could slip away [רד״ק, ביאור יש״ר]. She bound a red wool thread, dyed from a crimson worm, around the infant's wrist to serve as a clear identifying mark. Beyond its practical purpose, this red thread carried profound layers of meaning. Its crimson color foreshadowed the future priestly garments, which would incorporate similarly dyed wool [שפתי כהן]. Moreover, the midwife was unknowingly guided by divine inspiration. She tied the crimson thread, known in Hebrew as shani, to designate him as the firstborn, yet the very sound of the word hinted at his ultimate fate of being born second, or sheni [אור החיים].

Once the thread was secured, the hand retreated into the womb. Commentators differ on how exactly this withdrawal occurred. Some suggest that the infant simply pulled his hand backward on his own [רש״י, רד״ק]. However, others argue that an unborn child does not execute such deliberate, voluntary movements. Instead, they propose that the sheer physical force of the twin brother pushing forward is what shoved the infant and his marked hand back inside [מחוקקי יהודה].

The midwife's swift action was intended to decisively declare which child emerged first. The intense need to identify the firstborn in this specific situation raises a question, as this was not a conventional family structure where the eldest son would automatically receive a double portion of his father's inheritance. Commentators explain that the inherent sanctity of the firstborn is strictly dependent on the initial opening of the womb. Properly identifying this child carried weighty practical consequences. It secured his right to a double portion of his mother's estate and, more importantly, established his spiritual status for performing sacrificial services, a role held by firstborns before the Levites were selected. It also triggered the future commandment to redeem the firstborn son [פני דוד, פענח רזא].

Ultimately, the midwife's definitive ruling established lasting legal precedents. From her testimony, Jewish law derives the principle that a midwife is entirely trusted to testify and determine the identity of the firstborn among twins. Furthermore, the brief emergence and subsequent return of the infant's limb serves as the foundational source for complex laws regarding ritual impurity during childbirth, demonstrating that such laws can take effect even before a child is fully born into the world [תורה תמימה, צפנת פענח].