The terrible events of this chapter follow Judah’s venture into the world, and surely we are meant to see a connection between his compromise and the ills that followed. His sin costs him his two eldest sons’ lives.
An alternative interpretation is that the words ‘lest peradventure he die also’ explains why Judah offered Shelah to Tamar at all. He was afraid that if he failed to do this, Shelah also might be subject to God’s anger for failing like Onan to raise a child for his brother Er. Seen this way, his request for delay is honest and the reason given – that Shelah is too young at present – is genuine. But this interpretation seems to be ruled out by the way Jacob expresses his fear. The danger in his mind is one that affects both of Shelah’s brothers, and not just Onan. If Jacob had only been worried about Shelah’s failing to produce a child for Er, then only Onan’s death would be relevant, for Er’s death certainly had nothing to do with any levirate duty – he was the first to marry her. Judah’s fear was not that Shelah might be judged for failing like Onan to give Er a son, but that Shelah, like both Er and Onan, would be in danger simply by marrying her. In fact there were clear reasons why God had judged each of these brothers, and they had nothing to do with Tamar.