abstenerse

To abstain — most often heard in voting and elections ('el diputado se abstuvo'), but also generally for refraining from something (food, alcohol, an activity). Conjugates irregularly like tener, since it's built on that root.

• Dos senadores decidieron abstenerse en la votación final. — Two senators decided to abstain in the final vote.
• El médico le recomendó abstenerse de alcohol durante el tratamiento. — The doctor recommended he abstain from alcohol during treatment.
• Prefiero abstenerme de opinar sobre ese tema. — I'd rather refrain from giving an opinion on that topic.

It's always reflexive (abstenerse, not abstener) and always takes de before what you're abstaining from — 'abstenerse de algo', never 'abstenerse algo'.

• expression Abstenerse curiosos — A fixed phrase used for generations in Spanish classified ads and 'for sale'/'for rent' listings to discourage casual inquiries and time-wasters — one of the most recognizable everyday uses of abstenerse outside formal contexts.