What is the correct grammar particle for 'for'?

Question

If I want to say, for example,

I'm waiting for Jason

or

I'm not in this for the money

What would be the particle? Ni?

Answer 1

There is no direct equivalent. When it comes to particles and prepositions, you can never expect a one-to-one correspondence. At least に does not work for your examples. Weblio (English-Japanese dictionary for Japanese people learning English) lists over 20 definitions and over 50 possible translations of for. The correct particle would be に, へ, の, と or を depending on the sentence.

I'm waiting for Jason.
ジェイソンを待っています。

I'm not in this for the money.
お金のためにやっているのではありません。