It seems to be a quote, or a variation on a quote, from Martin Lomasney:
> Lomasney once advised a young follower, "Don't write when you can talk; don't talk when you can nod your head."[1]
The West End Museum[2] attributes the longer quote to him.
[1] https://en.wikipedia.org/wiki/Martin_Lomasney referencing https://www.jstor.org/stable/361565
[2] https://thewestendmuseum.org/the-life-legend-and-lessons-of-...
