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:
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.
It would be particularly great if there are examples where the delay did come at a cost.