Reference for Rosh Hashanah 45:2
וליעביד בין אמלא בין אחסר וכי מקלע ר"ח בע"ש לא ליעביד כלל וכיון דלא עבדינן מוצאי שבת ועבדינן אמלא מידע ידעי דחסר הוא
But why should we not light up whether for a full month or a defective month, and when New Moon is on Friday not light up at all, so that since we do not light at the termination of Sabbath, in spite of the fact th we usually light for a full month, people will know that it is defective? - This nevertheless may lead to errors, since people will say, This month is full, and the reason why they have not lit up is because they have been prevented.<span class="x" onmousemove="('comment',' Through having drunk too much on Sabbath, and become intoxicated (Rashi) . ouan');"><sup>2</sup></span> But why not light up for the full months and not at all for the defective months? - Abaye replied: So as not to deprive the public of two working days.<span class="x" onmousemove="('comment',' It was customary to abstain from work on New Moon (v. Tosaf. s.v.) . In this case the thirtieth day would always he kept as New Moon from doubt, and if the actual day fixed was the thirty-first, there would be two days New Moon. xurse xur,e');"><sup>3</sup></span>