The brief description on the title page (SuttaCentral) for SN 12.60 states, “The opening of this is similar to DN 14 Mahānidāna.” Not only should it probably say “this sutta,” it should also read “DN 15.”
In addition, it’s listed as having 0 parallels. I suggest someone have a look at EĀ 49.5: the second half is essentially the same as this one (and DN 15’s) with a more elaborate simile describing the depth of the Dhamma.