The fully charged battery is 4.2V and you said the forward voltage was "rated for" 3.8V. You never told us the mAh rating of your 18650 battery. If we assume 0.001 ohms (1 mohm) resistance between the battery leads and the led leads. that's
(4.2V-3.8V)/0.001 ohms = 400A.
We aren't freaking out. We are telling you that your approach to learning is stupid.
It doesn't matter how many leds you have or how much money you have. Your approach to learning is stupid because you are too impatient to do any research before taking action. It's your PHILOSOPHY (of electronics) that we are criticizing.
The idea that "I don't know what the fxxk I'm doing and I'm too lazy to ask so I'll just connect this led directly to the battery to see what happens. Why is that stupid ? Because what you don't know is that electronic components explode and project shrapnel at high velocity when subjected to high currents in short time periods.
You could have lost an eye , or both.
I'm outta here...