Full Idea
Heidegger is a relentless enemy of ahistorical, absolutist concepts of truth.
Gist of Idea
Heidegger says truth is historical, and never absolute
Source
report of Martin Heidegger (Being and Time [1927]) by Richard Polt - Heidegger: an introduction 1
Book Reference
Polt,Richard: 'Heidegger: an introduction' [Routledge 2003], p.5
A Reaction
I presume that if truth is not absolute then it must be relative, but Polt is a little coy about saying so. For me, anyone who says truth is relative doesn't understand the concept, and is talking about something else.