Answering to someone’s question that what does ‘necessary’ and ‘unnecessary’ talk refer to (or what are their differences), eminent Tabeyee, Hazrat ‘Ata Ibne Abi Rabah (R) replied:
Our pious predecessors used to limit their talks into the following FIVE POINTS:
a. The recitation of Kitabullah (the Holy Quran) and its discussion
b. The narration of the Ahadith and its discussion
c. Command the right and forbid the wrong
d. Discussion of the Ilm or sacred knowledge
e. Essential words of life and livelihood
(Then he said:) Will you deny these verses?
While (appointed) over you there are watchers, who are noble, writers (of the deeds) [Sura Infitar: 10-11]
When the two receiving angels receive (every human act to record it), seated (one) on the right and (one) on the left. Not a single word is uttered by one, but there is a watcher near him, ready (to record). [Sura Qaf: 17-18]
(He continued:) If our Book of Deed had been brought forth of us daily, hadn’t he been ashamed by seeing most of those unnecessary talks (recorded)? Won’t he feel pity and say: Alas! Most of the deeds are completely extraneous pertaining to the world and the afterlife!
From Suwarum-min Hayatut-Tabeyeen