Delayed speech as right speech

I was once told a story by the abbott of a monastery about how the Buddha once decided to delay his speech and said it only when it was the right time. Paraphrasing, the story is like this - > Two tribes were going to war over the waters of a river and the Buddha > wanted them to stop, but he knew that they were not in the right frame > of mind to listen to him. So he kept quiet. After 3 days of > fighting, when both sides were in pain from the fighting, the Buddha > decided to give them advice at that moment, when they were primed to > listen and they stopped the war immediately. Although he allowed many > people to die in waiting for the right moment, he saved a great many > more lives. If he had spoken right away and they'd rejected his advice, they > might also not have listened to him afterwards either. The abbott then advised me to remember this story as a model. And I did. I liked it a lot too. This was many years ago. The problem is, I recently decided to look up the story and found this story in the Mahāvaṃsa , of imminent war between the Sakyans and the Koliyans over the waters of the Rohini river. A key difference here is that the Buddha ***did not*** wait until the fighting had started. He showed up at the site where the armies had gathered. Still a nice story of the Buddha stopping a war, but not an example of delaying speech for the appropriate moment *even at some cost*. It's no longer possible for me to ask the abbott whether he meant this or another story or if he has a reference to another version of the same story which involved 3 days of battle. Instead, I'd like to ask the community about the main point: 1. Do you know of a canonical reference (from **any flavor of Buddhism**) where the Buddha or another prominent figure decided to delay a statement on account of timeliness and later said it with positive impact? To be clear, instances where the Buddha decided not to say something are numerous - I'm only looking for examples where he (or another person) did end up saying it later. **Edit:** Also, I know that the teaching on speaking at the appropriate time is quite clear - what I'm asking about is examples from the life of the ancients. 2. It would be particularly great if there are examples where the delay did come at a cost.