Actually it is a quotation from the Bible. It's Matthew 7:6 in Jesus's Sermon on the Mount to be exact.
"Do not give what is holy to the dogs; nor cast your pearls before swine, lest they trample them under their feet, and turn and tear you in pieces."
«Не давайте святыни псам и не бросайте жемчуга вашего перед свиньями, чтобы они не попрали его ногами своими и, обратившись, не растерзали вас».
Alas, he was crucified by the people he was preaching, healing, feeding and quenching and his main disciple renounced him three times.
So he himself contradicted this wisdom, for if there is one reasonable person ready to understand the value of the pearls in a throng of swines, maybe it's worth casting?
There are on-line web-cameras on the border crossing points, for example, this one monitors the main border crossing point Nekhoteevka-Goptovka which is the biggest such a point in Belgorod region and is situated on the road leading from Moscow to Kharkov:
Граница Online Нехотеевка
As you can see it's empty right now. In order to bring a 10-thousand crowd for making "disorders" in Kharkov Russians must have been used at least a hundred buses provided each bus contained a hundred persons. I've been periodically watching this camera for a few days - I've noticed no perceptible activity on this boarder-crossing point.
I also tried to find a single volunteers enlisting point in my native city which is right half-way between Moscow and Kharkov - no luck. Such things simply don't exist. Recent days people were busy with their jobs and buying presents for their women for the celebration of the Women's day, they don't have any reason to go invading Kharkov.
Also think about accommodations where all this "tourists" have to stay. Is there any tents, field-kitchens, as in Kiev's Maidan? There's nothing - nor in Kharkov nor in Donetsk nor in Lugansk which can be explained by the only reasonable presumption that most of those demonstrators are local inhabitants.
Of course nobody can prevent individual persons to cross the border on the legal basis and take part in whatever activities they like, but it's their own personal responsibility - no state or civic institute can be blamed for this.
By the way, I couldn't find such on-line cameras on the Ukrainian side of the border. Why?