The Torah in Parashat Vayeishev tells of the tragedies that befell the family of Yehuda, the fourth son of Yaakov. Yehuda’s son, Er, died after his marriage to Tamar, before begetting children. Following the practice of yibum – the levirate marriage – which, apparently, was customary even before the Torah was given, Yehuda had his second son, Onan, marry Tamar. Onan also died without begetting children (as he would purposely ejaculate outside Tamar’s body during intercourse to prevent conception), and thus Tamar was again left widowed. After Onan’s passing, Yehuda told Tamar to return to her father’s home until his third son, Sheila, grew up, because, as the Torah tells, Yehuda feared that Sheila would also die. However, even when Sheila grew older, Yehuda did not bring Tamar to marry him, prompting Tamar to take the bold action of posing as a prostitute and luring Yehuda into an intimate relationship in order to conceive from a member of the family.
Rashi (38:11) explains that Yehuda in truth had no intention of ever allowing Sheila marry Tamar, as he feared that she was somehow the cause of his two older sons’ deaths. The claim that Sheila was too young was, according to Rashi, just an excuse for sending Tamar back home, as in reality Yehuda did not plan on ever allowing her to marry Sheila.
The Ramban disagrees, noting that if Yehuda feared that marrying Tamar is what caused his sons to die, and for this reason did not want her to marry Sheila, he would have told this to Tamar, without misleading her into thinking that she could eventually marry Sheila. Tamar clearly expected to marry Sheila, and thus necessarily, the Ramban argues, this must have been Yehuda’s plan. The Ramban therefore explains that Yehuda realized that his two older sons died young because of their sinful behavior (as the Torah explicitly states – 38:7,10), and so he decided to delay Sheila’s marriage until he was older. He figured that Er and Onan married at too young an age, and this is what led to their sinful conduct for which they were killed. In order not to repeat this mistake, Yehuda wanted Sheila to grow older before marrying. However, Tamar was dismayed when Sheila became old enough – in her estimation – to get married, and Yehuda still refused to have her marry him. This interpretation is offered by Chizkuni and Seforno, as well.
Netziv, in his Ha’ameik Davar commentary, questions this approach, challenging the assumption that Yehuda was able to point to Er and Onan’s sinful conduct as the reason for their early deaths.
Chizkuni adds a different explanation, suggesting that perhaps Yehuda wanted Sheila to marry a different woman before then taking Tamar as a second wife. Yehuda wanted Sheila to fulfill his levirate obligation and marry Tamar, but he did not want Sheila to die without children, as his brothers did after marrying Tamar. He therefore planned for Sheila to marry and produce children with a different woman, and then marry Tamar. We might wonder, however, why, according to this theory, Yehuda would have thought to allow Sheila to marry Tamar at all, even after producing children with another woman, if he feared this marriage would cause Sheila to die.
Netziv takes a much different approach. In his view, Yehuda did not know the reason for his sons’ premature death, and so he feared that his family was plagued by a genetic defect of sorts which made his sons die young. He therefore told Tamar to return home and not to wait for Sheila to become old enough to marry, as he wanted to see if Sheila would die at a young age like his older brothers. In the end, however, even when Sheila grew older than the age at which Er and Onan died, Yehuda still did not have him marry Tamar, for some unknown reason (see Netziv’s comments to 38:26), and thus Tamar decided to boldly initiate an intimate encounter with Yehuda so she could bear a child.