Romeo and Friar Laurence are the only two characters in Act II scene iii of Romeo and Juliet by William Shakespeare. The friar is gathering herbs and plants to make his medicines, and of course he is talking to himself, out loud, so we can hear him ruminate on the plants which he is gathering. (He notes that the same plant has both the power to kill and to heal, depending on how it is used, which will be important information later.)
Romeo has just left Juliet's balcony and wants to ask the friar if he will marry the two of them. When he sees Romeo greeting him so cheerfully, the friar is surprised and makes the following speech:
What early tongue so sweet saluteth me?Young son, it argues a distempered headSo soon to bid good morrow to thy bed.Care keeps his watch in every old man’s eye,And where care lodges, sleep will never lie.But where unbruisèd youth with unstuffed brainDoth couch his limbs, there golden sleep doth reign.Therefore thy earliness doth me assureThou art uproused by some distemperature.Or if not so, then here I hit it right:Our Romeo hath not been in bed tonight.
The friar would not have been surprised to meet an old man like himself so early in the morning because they are often worried about things and cannot sleep, but young men are not usually up at this time because they don't have anything to worry about and should be sleeping.
First the friar wonders if Romeo is worried about something, but then he makes the more likely assumption: Romeo is here so early because he never went to bed last light. Romeo admits "[t]hat last is true; the sweeter rest was mine.
The remark about "sinning" is in the friar's next line:
God pardon sin! wast thou with Rosaline?
This comment could be "translated" as Friar Laurence's hope that Romeo has not "sinned" with Rosaline (the girl Romeo claimed to love so much just yesterday). He assumes that Romeo was with a girl all night and that they did something sexual which they should not have done.
Romeo is able to reassure the friar that he committed no sin, but of course he has a more difficult time convincing the friar that he now loves Juliet.