The Reichstag fire on 27 February 1933, led to the "improvisation" and approval of the Reichstag Fire Decree the next day, which impaired many of the civil liberties of the German people, and gave the National Socialists under Hitler the legal means to imprison those who were considered opponents to his government, and the ability to suppress publications against them. The document was, undoubtedly, one of the most important stepping stones towards a complete, one-party Nazi dictatorship. I find it hardly possible that a fire could break out, and in less than 24 hours Hitler manages to blame the Communists for the fire, convince the public, arrest thousands of members of the communist party all while creating an extremely significant legislation and attaining approval from Von Hindenburg in one day. Although I'm sure most of us question the legitimacy of the Reichstag fire, and all are suspicious of the convenience of the fire and extremely quick process of the elimination of Hitler's main political enemies in Germany and an attainment of increased power in one day, is there any proof (primary sources) that possibly indicate the Nazis as being responsible for the crime? I understand that the true instigator of the fire is still unknown, but I feel that the convenience of the event and the extremely fast elimination of Hitler's enemies along with his increased power in one day is reasonable grounds to suspect that it was a Nazi plot to attain further legal power and incriminate and silence his opponents.
In one of his "book reviews" in the LRB Richard J. Evans goes through both the various theories and the wider historiography surrounding the Reichstag Fire. As /u/cavetroglodyt notes, there is no conclusive evidence of a conspiracy and Evans outlines the trouble with arguments that claim otherwise. The general historical consensus is that the Nazis did not start the fire, but exploited it to build upon the already existing emergency legislation that allowed Hitler to cement his dictatorship.
As far as I know no conclusive proof in your sense has been discovered yet.
Everything I've read indicates that the draft for the so called Reichstag fire decree was made on the 28th of February and passed by the cabinet as well as President Hindenburg the same day.
You have to realize though that this in itself is not that suspicious. Similar decrees with the exact same phrasing, at least as in ยง1, had been passed before in 1932 and 1923. Hitler was already using a decree from the 4th of February that allowed him to temporarily imprison opponents and ban public assemblies and publications. The paragraph that effectively abolished federalism had precedence in the decree from 1932 that "allowed" the Reich to disband the Prussian government and let the chancellor rule that state in a personal union. Other measures that considerably increased the NSDAP's power were also instituted beforehand, such as the elevation of the SA to perform official police duties on February 22nd.
While the decree is important and, imo, maybe even more important than the formal laws passed in March, the deterioration of democratic rule began way before Hitler came to power and accelerated quickly after Jan. 30 culminating in the Reichstag fire decree .