The Quran

وَجَعَلَ فيها رَواسِيَ مِن فَوقِها وَبارَكَ فيها وَقَدَّرَ فيها أَقواتَها في أَربَعَةِ أَيّامٍ سَواءً لِلسّائِلينَ

Muhammad Asad

For He [it is who, after creating the earth,] placed firm mountains on it, [towering] above its surface, and bestowed [so many] blessings on it, and equitably apportioned¹ its means of subsistence to all who would seek it: [and all this He created] in four aeons.²

I.e., in accordance with divine justice, and not with human concepts of "equity" or "need".
Almost all the classical commentators agree in that these "four aeons" include the "two" mentioned in the preceding verse: hence my interpolation of the words "and all this He created". Together with the "two aeons" of verse 12, the entire allegorical number comes to six.