The Sabba Sutta (SN 35.23) (trans. Thanissaro) states:
The Blessed One said, "What is the All? Simply the eye & forms, ear & sounds, nose & aromas, tongue & flavors, body & tactile sensations, intellect & ideas. This, monks, is called the All. Anyone who would say, 'Repudiating this All, I will describe another,' if questioned on what exactly might be the grounds for his statement, would be unable to explain, and furthermore, would be put to grief. Why? Because it lies beyond range."
The commentary on this sutta by Thanissaro Bhikkhu states:
Furthermore, the following discourse (SN 35.24) says that the "All" is to be abandoned. At no point does the Canon say that nibbana is to be abandoned. Nibbana follows on cessation (nirodha), which is to be realized. Once nibbana is realized, there are no further tasks to be done.
Thus it seems more this discourse's discussion of "All" is meant to limit the use of the word "all" throughout the Buddha's teachings to the six sense spheres and their objects. As the following discourse shows, this would also include the consciousness, contact, and feelings connected with the sense spheres and their objects. Nibbana would lie outside of the word, "all." This would fit in with another point made several times in the Canon: that dispassion is the highest of all dhammas (Iti 90), while the arahant has gone beyond even dispassion (Sn 4.6; Sn 4.10).
This raises the question, if the word "all" does not include nibbana, does that mean that one may infer from the statement, "all phenomena are not-self" that nibbana is self? The answer is no. As AN 4.174 states, to even ask if there is anything remaining or not remaining (or both, or neither) after the cessation of the six sense spheres is to differentiate what is by nature undifferentiated (or to objectify the unobjectified — see the Introduction to MN 18). The range of differentiation goes only as far as the "All." Perceptions of self or not-self, which would count as differentiation, would not apply beyond the "All." When the cessation of the "All" is experienced, all differentiation is allayed.
On the other hand, Bhikkhu Bodhi wrote in the book The Connected Discourses of the Buddha Vol II:
On first consideration, it would seem that the six internal and external sense bases should be understood simply as the six sense faculties and their objects, with the term āyatana, base, having the sense of origin or source. Though many suttas lend support to this supposition, the Theravada exegetical tradition, beginning already from the Abhidhamma period, understands the six pairs of bases as a complete scheme of classification capable of accommodating all the factors of existence mentioned in the Nikayas. This conception of the six bases probably originated from the Sabba Sutta (35:23), in which the Buddha says that the six pairs of bases are "the all" apart from which nothing at all exists. To make the six bases capable of literally incorporating everything, the Vibhanga of the Abhidhamma Pitaka defines the mind base (manāyatana) as including all classes of consciousness, and the mental phenomena base (dhammāyatana) as including the other three mental aggregates, subtle nonsensuous types of form, and even the unconditioned element, Nibbāna (see Vibh 70-73).
So, Thanissaro Bhikkhu says that Nibbana is not included in The All. Bhikkhu Bodhi says Nibbana is included in The All. Who is right? And why?
What is also interesting is that Bhikkhu Bodhi's interpretation would put all types of consciousness within the classification of the six sense bases.