As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school, which bases its tenets on the doctrines laid out in the Brahma Sutras, a work by the sage Vyasa that summarizes and systematizes the philosophical teachings of the Upanishads. You can read the Brahma Sutras here. In any case, in Adhyaya 3 Pada 2 Sutra 4 of the Brahma Sutras, Vyasa says this:
sūcakaś ca hi śruter ācakṣate ca tadvidaḥ
(Not altogether) for it (the dream) is indicative (of the future), according to scripture; the experts also declare this.
This translation is written from the viewpoint of the Advaita philosopher Adi Shankaracharya, who interprets this Sutra as saying that even though dreams are an unreal creation of the Jiva, they still have an element of truth insofar as they can predict the future. (This is in contrast to other commentators who think this Sutra is saying that the fact that dreams predict the future imply that they're created by Paramatma, not the Jiva.) Here is what Adi Shankaracharya says in this section of his Brahma Sutra Bhashya:
Well then, as dreams are mere illusion, they do not contain a particle of reality?--Not so, we reply; for dreams are prophetic of future good and bad fortune. For scripture teaches as follows, 'When a man engaged in some work undertaken for a special wish sees in his dreams a woman, he may infer success from that dream-vision.' Other scriptural passages declare that certain dreams indicate speedy death, so, e.g. 'If he sees a black man with black teeth, that man will kill him.'--Those also who understand the science of dreams hold the opinion that to dream of riding on an elephant and the like is lucky; while it is unlucky to dream of riding on a donkey, &c.; and that certain other dreams also caused by special mantras or devatâs or substances contain a particle of truth.--In all these cases the thing indicated may be real; the indicating dream, however, remains unreal as it is refuted by the waking state.
Now the first Vedic verse that Adi Shankaracharya quotes is quoted by other commentators as well, and it occurs in this chapter of the Chandogya Upanishad:
yadā karmasu kāmyeṣu striyaṁ svapneṣu paśyanti samṛddhiṃ tatra jānīyāttasminsvapnanidarśane tasminsvapnanidarśan
If during sacrifices which are to fulfil certain wishes he sees in his dreams a woman, let him know success from this vision in a dream, yea, from this vision in a dream.
But my question is, where in the Vedas is the second verse from, the one that says that seeing a black-skinned man with black teeth in a dream implies that you'll die? I assume it must be from the Vedas since the Sutra says Shruti.