Genesis 38:17-18 "I'll send you a young goat from my flock," he said. "Will you give me something as a pledge until you send it?" she asked. He said, "What pledge should I give you?" "Your seal and its cord, and the staff in your hand," she answered. So he gave them to her and slept with her, and she became pregnant by him.
So Judah promises to pay her with a goat. Now, a goat at that time - according to sources - went for 10 drachmas. An architect got paid 2 drachmas a day - so Tamar was being offered a weeks wages of a well-paid professional. Not bad for 10 - minutes (or so :)). However, it's a little disturbing to think that Judah has this type of disposable income and instead of offering it to Tamar willingly as his widowed daughter-in-law, she has to trick him into it. Nevertheless, this is not about the money - so I'll get back on track.
Because he didn't have the goat with him, he wanted to know what he could give her as collateral until he could give her the goat. Now turning tricks on credit may have been something done back then - but I'm sure it's not done today. Still, he gave her his seal and cord - the equivalent of his driver's license. It was a sure sign of his identity - exactly who it was that was sleeping with her.
Now look at the last 5 words of these verses. Remember we had mentioned in the last post about this being nothing short of miraculous. Tamar is pregnant! There are married couples who pay a years worth of income in order to become fertile and have children - Tamar gets one shot and 'bang' she's with child. God does work miracles - whether we want to see it as such or not - it's all in His timing - in His perfect plan - in His infinite mercy and grace.