'must abstain' is correct and usable in written English.
You can use it when suggesting that someone should not do something, such as in the sentence "We must abstain from eating unhealthy snacks."
This episode finally convinced him that he must abstain from public religious endeavour until he reached the priesthood.
I have no doubt that the ice creams will be delicious, but this weekend I must abstain.
Current NHSBT guidelines say prospective recipients with liver-related disease must abstain from alcohol ahead of the transplant and for their rest of their lives.
Since Glencore must abstain from voting, a group of investors with just 16 percent of Xstrata shares can block the merger.
As part of his probation, he must abstain from drugs and avoid establishments where alcohol is the main source of income.
As part of the drug offender probation program, Strawberry will be subjected to at least two random urine tests a month and must abstain from alcoholic beverages or illegal drugs.
He has taken a vow, and observed the obligatory 15-days fasting period when a strictly vegetarian diet must be followed and the devotee must also abstain from alcohol, tobacco and sex.
If patient capacity is limited, firms must either abstain from quality competition (i.e., increasing volume) or invest in extra capacity which will be increasing marginal costs.
He must also abstain from alcohol and report twice a week to a police station, according to Reuters.
To participate, each participant must have abstained from handwashing for at least 1 hour before sampling and must have handled the dog within that period.
They are the people whom we must get to abstain.
