Why does Claudius invite Rosencrantz and Guildenstern to speak with him and Gertrude? Supportive quote please?

He wants them to spy on Hamlet.

"That, being of so young days brought up with him

And since so neighbored to his youth and 'havior,

That you vouchsafe your rest here in our court

Some little time so by your companies

To draw him on to pleasures and to gather,

So much as from occasion you may glean,

Whether aught, to us unknown, afflicts him thus

That, opened, lies within our remedy."