A children’s picture book, published no later than 1987.
It’s about a mouse who, though warned not to, goes on an adventure to the pond (lake?) He meets a group of frogs (toads?) who repeat everything twice. They call him “Mouse-Mouse.” An animal attacks and they flee. Semi-realistic illustration.
It isn’t your book, but the description puts me in mind of Majorie Flack’s “Walter the Lazy Mouse”. Walter the mouse sleeps so much his family tends to ignore him, (it doesn’t help that he has dozens of brothers and sisters) and he is left behind when they move across the meadow. Walter does get up and tries to find his family; when he goes exploring he meets up with three friendly but very forgetful frogs. Walter does learn to be more industrious, he has to build a house for himself, and he learns to visit the frogs every day, otherwise they keep forgetting who he is. When autumn comes Walter starts to feel the chill, fortunately he finally does find his family by then. He promises to meet the frogs next summer.
As I said, this probably isn’t your book, but it is a similar, and very pleasant, story. Good luck!
I was also thinking Walter the Lazy Mouse.
Consider this one solved; it was indeed Walter the Lazy Mouse! The part about fleeing from an animal was just my faulty memory.