When we start sentences with something like "To the best of our knowledge, ..." or"To achieve this, ...", do we need the commas? For example, which one is correct between "To the best of our knowledge, he is not coming." and "To the best of our knowledge he is not coming."?
I tried to look at the rule book for using comma and did not find a rule that applies; thus perhaps commas are not needed. However, I saw commas quite often. It is even there in the example in the merriam-webster dictionary: "To the best of his knowledge, no one had called all morning."