The scholars differed concerning the meaning of Allah's "descent" in the narrated hadith:
Our Lord - Blessed and Exalted be He! - descends every night to the lowest heaven in the last third of the night and says: Who is supplicating Me so that I may answer him? Who is asking forgiveness from Me so that I may forgive him?
It must be made clear here that the vast majority of the Salaf believe in this hadith (the descent of Allah to the lowest heaven) as it is without specifying, declaring Allah to be trascenderant above modality (kayfiyya) and likeness to his creation (tashbih). This position is reported by al-Bayhaqi and others from the four Imams, Sufyan ibn `Uyayna, Sufyan al-Thawri, Hammad ibn Salama, Hammad ibn Zayd, al-Awza`i, al-Layth, and others.
Some have made a difference between a kind of interpretation that is likely and current in the linguistic usage of the Arabs, and another kind which is far-fetched and archaic, interpreting in the former case and committing the meaning to Allah in the latter. This is reported from Malik, and among the Khalaf it is asserted decisively by Ibn Daqiq al-`EId (d. 702). [Fath al-Bari]. The following are the detail of these differences:
Al-Bayhaqi reports that Al-Ash`ari said: "What is meant by the descent is an act brought to be by Allah in the nearest heaven every night, which the Prophet (blessings and peace of Allah be upon him) has named a descent, without movement nor displacement. Exalted is Allah above the characteristics of creatures!"
Al-Qurtubi said that the hadith is elucidated by that related by al-Nasa'i in his Sunan al-Kubra and `Amal al-Yawm wa al-Layla whereby the Prophet peace and blessings of Allah be upon him said:
((Allah waits until the first part of the night is over, then He orders a herald (munadiyan) to say: Is there anyone supplicating so that he may be answered, anyone begging for forgiveness so that he may be forgiven, any petitioner so that he may be granted his request? [An-Nasa’i].
The above narration is confirmed by the hadith of `Uthman ibn Abi al-`As al-Thaqafi from the Prophet (blessings and peace of Allah be upon him).
The gates of heaven are opened in the middle of the night and a herald calls out: Is there anyone supplicating so that he may be answered? Is there anyone asking so that he may be granted? Is there anyone afflicted so that he may be delivered? At that time there is no Muslim who invokes for anything except Allah answers him, except the adulteress who runs after her pleasure and her intimate companion. [Tabarani and Ahmad].
Thus the calling out, in al-Qurtubi's view, is directly attributed to Allah in Bukhari and Muslim's narrations in order to highlight His regard and His emphasis, as when one says: "The sultan calls out for this," whereas it is actually a herald who calls out the sultan's order as elucidated in the above two versions.
This is confirmed by Imam Malik's statement: "It is our Blessed and Exalted Lord's command which descends; as for Him, He is eternally the same, He does not move or go to and fro," [Siyar A`lam al-Nubala'] although it is established that Malik forbade discourse of any kind about the hadiths of Allah's attributes, preferring not to interpret the hadiths of descent one way or the other and that he said about them: "Let them pass without entering into modality."
Nevertheless, not all the Salaf let them pass, as al-Bayhaqi relates from the Tabi`i Hammad ibn Zayd that he interpreted Allah's descent to the nearest heaven as "His turning to" (nuzuluhu iqbaluhu). [Al-Bayhaqi].
Al-Bayhaqi said: "The safest method is to believe in them without modality, and to keep silence concerning what is meant except if the explanation is conveyed from the Prophet himself, in which case it is followed." The proof for this is the agreement of the scholars that the specific interpretation is not obligatory, and that therefore the commitment of meaning to Allah is safest.
Abu Bakr ibn Furak has said that some of the masters have read it yunzilu - "He sends down" - instead of yanzilu - "He descends" - that is, He sends down an angel. This is strengthened by al-Nasa'i's narration through al-Aghurr from Abu Hurayra and Abu Sa`id al-Khudri: "Allah waits until the first part of the night is over, then He orders a herald to say: Is there anyone supplicating so that he may be answered?..."  There is also the hadith of `Uthman ibn Abi al-`As: "The gates of heaven are opened in the middle of the night and a herald calls out: Is there anyone supplicating so that he may be answered?..." Al-Qurtubi said: "This clears all ambiguity, and there is no interference by the narration of Rifa`a al-Juhani whereby "Allah descends to the nearest heaven and says: I do not ask about My servants anyone besides Myself," for there is nothing in this which precludes the above-mentioned interpretation.
Al-Baydawi said: Since it is established with decisive proofs that the Exalted is superior above having a body or being circumscribed by boundaries, it is forbidden to attribute to Him descent in the sense of displacement from one place to another place lower than it. What is meant is the light of His mercy: that is, He moves from what is pursuant to the attribute of Majesty entailing wrath and punishment, to what is pursuant to the attribute of Generosity entailing kindness and mercy."
However, the sound opinion is that Allah descends to the lowest heaven as He has declared and in the manner that befits His Majesty. We are not obliged to comprehend His manner of descent, which is something exclusive to the knowledge of Allah. Therefore, we have to accept and believe in it without questioning how and what happens to the throne when he has descended because the knowledge of that has not been conveyed to us. There is nothing like unto Allah and He is All-Hearing All-Seeing. Allah knows best.
Written by Dr. F.G. Haddad with little modifications.
For more details see the source: (http://www.sunnah.org/aqida/haddad/Allah's%20Descent1.htm).