The similarity between certain concepts in Transcendent Philosophy and Heidegger’s philosophy are so striking that the temptation to compare them often overrides their contextual and historical differences. Among such notions are "relational existence" (wujūd rābiṭ) and "reference". Mullā Ṣadrā took great pride in formulating the concept of relational existence, extolling it to such an extent that he regarded it as the key to "the completion of wisdom" and "the perfection of philosophy." Indeed, the "transcendent" character of his philosophy owes more to this concept than perhaps any other. Heidegger’s notion of "reference"—along with its related concept of "sign" - appears remarkably close to Ṣadrā’s relational existence. This paper begins by explicating each concept independently before analyzing their common ground. Mullā Ṣadrā offers an account of “existence” for the realities of world that possesses purely ‘through-another’ (li-ghayrihi) aspect, and is never analyzable as "in-itself" (fi nafsihi), not even in the mind. He terms this mode of being as relational existence and emphasizing its distinction from the concept of "relative existence" (wujūd rābiṭī), which earlier philosophers had attributed to dependent entities and which retained both "through-another" and "in-itself" dimensions. Heidegger, on the other hand, through his novel definition of the world by considering it as a field of referential relations, rather than a collection of entities, stripped worldly entities of any "in-itself" quality and reduced them to "signs." This article presents a comparative study of these innovations.