Sir, yes sir! 😒

Link to Guidelines which you can also find on top of this site under "Help"

And quote directly from that text for the lazy:

Won gifts must be activated on the Steam account used during registration, and they cannot be regifted [...]

And in the FAQ similar things are also mentioned at least twice

If I win a game, can I regift, trade, sell, or remove it from my Steam account?

According to our guidelines, no, all games you win must remain activated and redeemed on the Steam account you used during registration. [...]

Can I enter a giveaway for a friend?

You should only enter to win giveaways for yourself, and if you win a game, it must be activated and redeemed to the Steam account you used during registration. [...]