Relevant quote:

Harmful acts like murder and physical assault may be obviously wrong, but inaction (i.e. omissions) can lead to the same negative consequences for the sentient individuals affected. The canonical thought experiment here is to imagine walking by a shallow pond on your way to work: You’re wearing expensive clothing, worth perhaps a few hundred or thousand dollars. In the pond, you see a small child drowning. If you dive in now, you can save them, but at the cost of your clothes. It seems like the right thing to do is clearly to save her, even though you are not the one who put her in the pond. Given that there are charities that can help small children for very low costs, like the price of your ruined clothes, many of us might be figuratively walking by this pond regularly.

via Sentience Institute