I guess, six months is too early. Though, I, myself an Indian, and we love spicy food but I did not introduce my child to spices at this age. And no matter which culture you belong to, introducing spices to a kid always remain a big question.
I guess, to keep your husband's word, you can still introduce your kid to cinnamon or a pinch of haldi in her food but should let her turn atleast One, to proceed.
Else the best way to make your husband that your baby is too young to be given spices, you can make a visit to the baby's PD, and he will himself educate him.
http://wholesomebabyfood.momtastic.com/tipspices.htm
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