When Does Allah Descend to the Lowest Heaven?
Question

"...When half o a third of the night passes by, Allah descends to the lowest heaven and says: 'No one asks more about my servants than myself. Who is asking me, so I can give to him? Who is calling upon me, so I can answer him? who is seeking my forgiveness, so I can forgive him?'". I got two questions about this hadith.
How saheeh ( or correct ) is this hadith.
And second, what meaning is this hadith?
Praise be to Allah.Degree of the Hadith about the descent of Allah to the lowest heaven
This Hadith is authentic and it  is proven in the soundest two books after the Book of Allah. It was narrated by Al-Bukhari in his Sahih (1145) and by Muslim (1261) from Abu Hurayrah (may Allah be pleased with him), that the Prophet (peace and blessings of Allah be upon him) said: “The Lord descends every night to the lowest heaven when one-third of the night remains and says: ‘Who will call upon Me, that I may answer Him? Who will ask of Me, that I may give him? Who will seek My forgiveness, that I may forgive him?’” 
This Hadith was narrated from the Prophet (peace and blessings of Allah be upon him) by approximately twenty-eight of the Companions (may Allah be pleased with them) and the Ahl Al-Sunnah unanimously agreed that it is to be accepted. 
Meaning of the descent of Allah to the lowest heaven
It should be noted that the descent of the Lord – may He be Exalted – to the lowest heaven is one of the actions that are attributed to Him and has to do with His will and wisdom. It is descending in a real sense, in a manner that befits His Majesty and Might. Allah descends however He wills, whenever He wills. Glory be to Him, there is nothing like unto Him and He is the All-Hearing, All-Seeing. 
Refuting allegations about the meaning of descending
It is not permissible to distort the meaning of the Hadith by saying that what is meant is that His command or mercy descends, or that one of His angels descends. This is false for several reasons: 

This misinterpretation goes against the apparent meaning of the Hadith. The Prophet (peace and blessings of Allah be upon him) attributed descent or the act of descending to Allah, and the basic principle is that a thing is attributed to the one who does it, so if it is attributed to someone else, that is a distortion that goes against this basic principle. 

We know that the Messenger (peace and blessings of Allah be upon him) is the most knowledgeable of all people about Allah, and that he (peace and blessings of Allah be upon him) is the most eloquent of mankind and the most truthful in what he says. There are no lies in his speech and it is impossible for him to attribute something to Allah that is not one of His names or attributes or actions or rulings. Allah says (interpretation of the meaning):
“And if he (Muhammad) had forged a false saying concerning Us (Allah), We surely would have seized him by his right hand (or with power and might), And then We certainly would have cut off his life artery (aorta).” [Al-Haqqah 69:44-46] 
Moreover the only intention of the Prophet (peace and blessings of Allah be upon him) was to guide mankind, so if he said, “Our Lord descends” and someone else says something that runs contrary to the apparent meaning of these words, such as saying that His command descends, then we say: Do you have more knowledge about Allah than the Messenger of Allah (peace and blessings of Allah be upon him)? The Messenger (peace and blessings of Allah be upon him) said, “Our Lord descends” but you say His command descends. Or are you more sincere towards the ummah than he was, since he (allegedly) concealed what he was supposed to tell them and told them something different. Undoubtedly the person who tells the people one thing but means something else is not sincere towards them. Or do you think that you are more eloquent than the Messenger of Allah (peace and blessings of Allah be upon him)?! Undoubtedly such a misinterpretation implies that one is accusing the Messenger (peace and blessings of Allah be upon him) of some kind of shortcoming that a Muslim can never accept on the part of the Messenger of Allah (peace and blessings of Allah be upon him).  

The descent of His command and mercy is not restricted to this part of the night, rather His command and mercy descend all the time. If it is said that what is meant is a specific command or specific mercy which does not happen all the time, the answer to that is that if we assume that this interpretation is correct, then the Hadith indicates that where the descent of this thing ends is in the lowest heaven, so what benefit can it be to us if mercy descend to the lowest heaven without reaching us? Why would the Prophet (peace and blessings of Allah be upon him) even tell us about it?
The Hadith indicates that the One Who descends says: “Who will call upon Me, that I may answer Him? Who will ask of Me, that I may give him? Who will seek My forgiveness, that I may forgive him?” No one can say that except Allah, may He be Exalted. (See: Majmu` Fatawa wa Rasa’il Ash-Shaykh Muhammad ibn Salih Al-`Uthaymin, 1/203-210)

For more details, please refer to the following answers: 11035 , 49678 , and 992 .         
And Allah knows best.