be vigilant

References in classic literature ?
'The dogs do right to be vigilant. Take a glass of wine?'
Police are urging people in the area to be vigilant after cops were told about somebody sneaking through a garden in the Bellevue Park area of the town.
"" the I urge local people to be vigilant of what might be lying around KIERON SMYTH belfast yesterday
He asked parents to be vigilant as cartels may take advantage of the situation to make quick money.
"I have just spoken to the police who have asked me to ask parents to be vigilant walking home and remind their children of the stranger danger message.
Comelec: Be vigilant against people manning checkpoints
He however after getting assurance that agencies would be vigilant next time, disposed of the matter.
He said, 'Don't go away after voting, stay back to monitor your votes, be vigilant and prepare for prospective riggers who would come around.'
"We all have a duty to be vigilant against abuses of animal welfare and I will continue to work closely with the RSPCA to help improve standards of animal welfare in Wales and across the UK."
Through the columns of your esteemed daily, I appeal to the concerned authorities to look into the matter; and people to be vigilant. Kashfa Zia
Global Banking News-April 6, 2018--Singapore central bank asks banks to be vigilant against cyber threats
I will be interested to hear from Mr Cotter regarding whether there has been an increasing trend in these Hanoi-style burglaries and I would appeal to people to be vigilant and on their guard."