Halliday & Matthiessen (2004: 455-6):
Verbs used in reporting statements and questions are often the same as those used in quoting; … but there is one significant difference. In quoting, the independent status of the proposition, including its mood, is preserved; hence the speech function is as explicit as in the ‘original’. In reporting, on the other hand, the speech function is, or may be, obscured, and is therefore made explicit in the reporting verb. Three things follow. (1) In quoting, the word say can project sayings of every mood, whereas in reporting we find say, ask, and tell … (2) Many semantically complex verbs for elaborated speech functions are used only in reporting, for example insinuate … These verbs are seldom used to quote; there is too much experiential distance between them and the actual speech event. (3) On the other hand, many verbs that assign interpersonal and/or behavioural features to the speech event, and are used to quote, especially in narrative contexts, are never used to report because they do not contain the feature ‘say’.