Before anybody could respond to this ominous pronouncement, the dormitory doors opened again and Mr. and Mrs. Weasley hurried up the ward.  They had done no more than satisfy themselves that Ron would make a full recovery on their last visit to the ward; now Mrs. Weasley siezed hold of Harry and hugged him very tightly.  “Dumbledore’s told us how you saved him with the bezoar,” she sobbed.  “Oh, Harry, what can we say?  You saved Ginny . . . you saved Arthur . . . now you’ve saved Ron . . .”

“Don’t be . . . I didn’t . . .” muttered Harry awkwardly.

“Half our family does seem to owe you their lives, now I stop and think about it,” Mr. Weasley said in a constricted voice.  “Well, all I can say is that it was a lucky day for the Weasleys when Ron decided to sit in your compartment on the Hogwarts Express, Harry.”

Harry Potter and the Half-Blood Prince – J.K. Rowling