Depends on which Authority and the period in which you are looking.
For the US, you are, of course, correct.
Australia, for example in years gone by, put the requirement in the certification sections (ANO 101.5 - BCAR certification - and 101.6 - CAR/FAR certification) as was the philosophy in a number of differences with the major Authorities.
Memory's scratching a tad and I would need to dig out a couple of original AFMs to double check on landing distances .. but I recall that the same applied in the UK under the BCARs.
I resile in mortification
... but it's minor point in the overall pursuit of pedantry, I would suggest.
As to origin, my guess is ICAO around the 50s. One of our number here in the sandpit has a well-thumbed copy of the then report of wise words and, on occasion, quotes selectively from it for our benefit .. we can but wait and see on this occasion.