There’s a few suttas of what I call “signpost” suttas which teach you how to discern true dhamma from false dhamma.
Gotami sutta is one
"Gotami, the qualities of which you may know, ‘These qualities lead to passion, not to dispassion; to being fettered, not to being unfettered; to accumulating, not to shedding; to self-aggrandizement, not to modesty; to discontent, not to contentment; to entanglement, not to seclusion; to laziness, not to aroused persistence; to being burdensome, not to being unburdensome’: You may categorically hold, 'This is not the Dhamma, this is not the Vinaya, this is not the Teacher’s instruction
and another
Upāli, you might know that certain things don’t lead solely to disillusionment, dispassion, cessation, peace, insight, awakening, and extinguishment. You should definitely bear in mind that such things are not the teaching, not the training, and not the Teacher’s instructions. You might know that certain things do lead solely to disillusionment, dispassion, cessation, peace, insight, awakening, and extinguishment. You should definitely bear in mind that such things are the teaching, the training, and the Teacher’s instructions.”
And also you don’t need to rely entirely on texts to begin with if you have Supermundane right view:
Please, Bhaddiya, don’t go by oral transmission, don’t go by lineage, don’t go by testament, don’t go by canonical authority, don’t rely on logic, don’t rely on inference, don’t go by reasoned contemplation, don’t go by the acceptance of a view after consideration, don’t go by the appearance of competence, and don’t think ‘The ascetic is our respected teacher.’ But when you know for yourselves: ‘These things are unskillful, blameworthy, criticized by sensible people, and when you undertake them, they lead to harm and suffering’, then you should give them up.
The sutta then goes into a talk about the 3 poisons.
This is basically the core dhamma right there, seeing the 3 poisons manifest and putting an end to them.
You can put an end to greed by using the preception of dispassion (i.e. the drawbacks anicca, dukkha, anatta) against a perception of passion (craving).
If you want to understand the core dhamma, which is that of giving up craving to stop suffering, then the 4 nikayas are sufficient.
Keep in mind, you’re not always going to have good memory or access to the texts, so it’s best to focus on what makes the dhamma unique, why is it different than everything else, what is the subtle and hard to see teaching. What makes one an Ariya? What is Supermundane right view? What is visible “here and now”?
And to start you off,
- Giving up the identity view fetter means not assuming the 5 aggregates to be the self
- A being or self is actually the 3 poisons (satta sutta)
- The dhamma being visible here and now means seeing the 3 poisons (AN 6.47)
- The dhamma being unique means the noble truths and dependent origination
- All of the above combined is Supermundane right view, which basically means unwholesome actions, thoughts, and intentions are born of the 3 poisons, not some ambiguous self, and this unwholesomeness is suffering, and how this unwholesomeness manifests as suffering is dependent origination, and the way to put an end to it is the noble eightfold path, and once again this all visible here and now, not “there and later” as in some future life.