Yes. But they are not 'commandments', but precepts (i.e. to
abstain) to be followed if one wants to avoid suffering bad karmic
fruition and rebirth in the lower realms (and nobody wants that).
As a Buddhist the very least is of course at least prior to
enlightenment is to prevent bad rebirths and have a good rebirth,
but that is also not our ultimate goal. Hence the importance of
abiding strictly to precepts.
Adultery is third. BTW, we don't call it 'sin', in Buddhist
terminology we simply say bad karma, or unwholesome action.
The 5 precepts are as follows:
1) Abstain from taking life.
2) Abstain from taking what is not given.
3) Abstain from sexual misconduct.
4) Abstain from from false speech.
5) Abstain from drinks and drugs that cause heedlessness.
what if u dont follow them? whats the consequence?