Who are the siddeeqoon? What are their characteristics?
Question

Who are the siddeeqoon [the strong and true in faith, or the first and foremost to believe] according to the Qur’an and Sunnah? What are their characteristics and virtues? How can a person become one of them?
Praise be to Allah.Firstly: 
High ambition, sublime aims and the desire to attain high status and draw closer to Allah by doing righteous deeds and refraining from that which is forbidden are all things that are prescribed and encouraged in Islam. Al-Bukhaari (7423) narrated from Abu Hurayrah that the Prophet (blessings and peace of Allah be upon him) said: “When you ask of Allah, ask Him for al-Firdaws, for it is the middle of Paradise and the highest part of Paradise; above it is the Throne of the Most Gracious, and from it flow the rivers of Paradise.” 
There is nothing wrong with the Muslim praying to be among the righteous close friends of Allah, or the sincere siddeeqoon.
Secondly: 
The close friends of Allah, may He be exalted, are the pious ones among His creation who fear Him. Everyone who is pious is a close friend of Allah, but that close friendship varies according to the level of a person’s faith and piety or fear of Allah. The highest status thereof after that of the Prophets is the status of the siddeeqoon; those who attain this status are the siddeeqoon. 
Allah, may He be exalted, says (interpretation of the meaning):
“And whoso obeys Allah and the Messenger (Muhammad (blessings and peace of Allah be upon him)), then they will be in the company of those on whom Allah has bestowed His Grace, of the Prophets, the Siddeeqoon (those followers of the Prophets who were first and foremost to believe in them, like Abu Bakr As-Siddeeq), the martyrs, and the righteous. And how excellent these companions are!” [an-Nisa’ 4:69]
“And those who believe in (the Oneness of) Allah and His Messengers, they are the Siddeeqoon (i.e. those followers of the Prophets who were first and foremost to believe in them), and the martyrs with their Lord, they shall have their reward and their light” [al-Hadeed 57:19]. 
Al-Khaazin (may Allah have mercy on him) said: 
The siddeeq (explained here as one of “those followers of the Prophets who were first and foremost to believe in them” is the one who speaks the truth. The siddeeqoon are those followers of the Messengers who followed their path after they were gone, until they met them. And it was said that the siddeeq is the one who believes in the entire religion, to the extent that he has no doubt at all about his faith."(Tafseer al-Khaazin  1/397) 
Al-Qurtubi (may Allah have mercy on him) said: 
The word siddeeq is a grammatically intensive form which indicates a high level of belief. The siddeeq is the one who confirms with his actions what he says with his tongue. And it was said that they (the siddeeqoon) are the best of the followers of the Prophets who were the first of them to believe, such as Abu Bakr as-Siddeeq."(Tafseer al-Qurtubi 5/272) 
As-Sa‘di (may Allah have mercy on him) said: 
The siddeeqoon are those who reached the highest levels of faith, righteous deeds, beneficial knowledge and true certainty."(Tafseer as-Sa‘di  p. 841) 
Ibn al-Qayyim (may Allah have mercy on him) said: 
The highest level of sincerity is that of the siddeeq; it is perfect submission to the Messenger (blessings and peace of Allah be upon him), accompanied by perfect sincerity towards the One Who sent him."(Madaarij as-Saalikeen  2/258) 
For more information, please see the answer to question no. 2424 . 
Thirdly: 
Whoever follows the Siddeeqoon in their path of sincerity, belief, piety and righteousness will be one of them and will be gathered with them (on the Day of Resurrection). Allah, may He be exalted, says (interpretation of the meaning):
“And whoso obeys Allah and the Messenger (Muhammad (blessings and peace of Allah be upon him)), then they will be in the company of those on whom Allah has bestowed His Grace, of the Prophets, the Siddeeqoon (those followers of the Prophets who were first and foremost to believe in them, like Abu Bakr As-Siddeeq), the martyrs, and the righteous. And how excellent these companions are!” [an-Nisa’ 4:69]. 
Whoever wants to strive to reach this status and for Allah to bestow it upon him, and to be one of its people, must have perfect sincerity in word and deed, and fear Allah privately and in public.
For more information, please see the answer to question no. 107283 . 
And Allah knows best.