Friar Lawrence is an adviser to both Romeo and Juliet in William Shakespeare's Romeo and Juliet, and he is a bad adviser on all accounts. In Act V scene iii, Romeo reaches Juliet's tomb and, thinking she is dead, kills himself. The friar arrives, too late, of course, and Juliet wakes up. When he realizes what has happened, he tries to get Juliet to leave the tomb, suggesting that God had a different plan than their (his).
I hear some noise. Lady, come from that nest
Of death, contagion, and unnatural sleep: A greater power than we can contradict Hath thwarted our intents. Come, come away. Thy husband in thy bosom there lies dead; And Paris too. Come, I'll dispose of thee Among a sisterhood of holy nuns: Stay not to question, for the watch is coming; Come, go, good Juliet, [Noise again]
I dare no longer stay.
Friar Lawrence’s words have absolutely no affect on the distraught girl, and promising to take her to a convent was not any incentive for her to leave. The cowardly friar hears noises outside and leaves Juliet alone.
The specific line to which you refer is the friar’s description of the tomb, full of “death, contagion, and unnatural sleep.” Ironically, the very man who wanted Juliet to go there is now the man who claims it is an unhealthy place and she should leave. Ironically, too, he leaves her there, alive in a dead place, and comes back (by force) to find that she is now part of the “death, contagion, and natural sleep” he was so worried just a short time ago.