This thesis by Robert Tulip is interesting, given Levinas' ethical turn against Heidegger's ontology. It explores through:

an analysis of texts including Being and Time, An Introduction to Metaphysics and the Letter on Humanism, that Heidegger's existential ontology contains a significant ethical dimension. His focus on the 'question of the meaning of Being' gives the impression that his writings had little relation to ethics, but his thought must be interpreted in ethical terms because his phenomenological analysis of human existence (Dasein) understood meaning and truth in relation to humanity.

If these existential phenomena are excluded from the domain of philosophical truth, as demanded by traditional metaphysics, the search for truth will be forced to relegate major practical areas of ethical concern to the status of passionate opinion and will be unable to comment. The traditional separation of ontology and ethics underlying this attitude was formalised by David Hume, whose doctrine that reason is the slave of the passions implied that interest, rather than logic, was the basis of morality, and that statements of fact, the only proper concern of ontology, can provide no guidance about what we ought to do. In similar vein, Kant, who held that the twin sources of philosophy are “the starry heavens above and the moral law within”, held that these two are respectively the objects of separate critiques of pure and practical reason