First, here is the letter.

Eat heartily." Grimaud smiled; and with his eyes fixed upon the glass which Athos held in his hand, he ground the paper well between his teeth and then swallowed it.
"Bravo, Monsieur Grimaud!" said Athos; "and now take this.

That's well.
We dispense with your saying grace." Grimaud silently swallowed the glass of Bordeaux wine; but his eyes, raised toward heaven during this delicious occupation, spoke a language which, though mute, was not the less expressive.
"And now," said Athos, "unless Monsieur Cardinal should form the ingenious idea of ripping up Grimaud, I think we may be pretty much at our ease respecting the letter." Meantime, his Eminence continued his melancholy ride, murmuring between his mustaches, "These four men must positively be mine.".