Parsley seed must be soaked before you sow it.
Some plants seem to attract myth and superstition and parsley is one. The truth is parsley is slow to germinate and gardeners can be impatient, so people have looked to ways to speed things up. To this end it is often said you need to soak parsley seed to get it to germinate; however it will germinate without any soaking. What if any difference soaking makes how quickly it germinate I do not know, but have you ever tried to thinly sow wet seeds? You can’t, they just form a wet clump.
Personally, I just scatter the seed over a patch of fine earth and water it just as if were grass seed and wait. In a few weeks it starts to germinate and once the first true leaves appear you can easily spot what parsley and what isn’t so you can weed and thin as needed.