Praise be to Allaah.
Shaykh Muhammad al-Ameen al-Shanqeeti said in his book Daf Ayhaam al-Idtiraab an Aayaat al-Kitaab (p. 158):
The aayah (interpretation of the meaning) And, verily, a day with your Lord is as a thousand years of what you reckon [al-Hajj 22:47] indicates that the length of a day with Allaah is a thousand years. The same is indicated by the aayah (interpretation of the meaning) He arranges (every) affair from the heavens to the earth, then it (the affair) will go up to Him, in one Day, the space whereof is a thousand years of your reckoning. [al-Sajdah 32:5]. Another aayah indicates something different (interpretation of the meaning): The angels and the Rooh [Jibreel] ascend to Him in a Day the measure whereof is fifty thousand years [al-Maaarij 70:4].
There are two ways in which these aayaat may be reconciled:
The first was reported by Ibn Abi Haatim via Sammaak from Ikrimah from Ibn Abbaas: the day of a thousand years mentioned in Soorat al-Hajj is one of the six days in which Allaah created the heavens and the earth; the day of a thousand years mentioned in Soorat al-Sajdah is the length of time it takes for a matter to go up to Allaah; and the day of fifty thousand years is the Day of Resurrection.
The second (way of reconciling the aayaat) is that what is meant by all of them is the Day of Resurrection, and the difference in the time span depends on whether a person is a believer or a kaafir. This is indicated by the aayah (interpretation of the meaning): Truly that Day will be a Hard Day, far from easy for the disbelievers. [al-Muddaththir 74:9-10]. These two suggestions were mentioned by the author of al-Itqaan. And Allaah knows best.