Allah is in no need of having an associate
The Messenger of Allah (PBUH) said in narration of Abu Hurayrah that Allah, the Most High and Exalted said: "I am the One who does not stand in need of a partner, if anyone does anything in which he associate anyone else with Me, I shall abandon him with one whom he associates with Me" (Sahih Muslim 2985).
Commentary:
There are two types of polytheism: major polytheism and minor polytheism, both are grave sins that lead their perpetrators to destruction and both necessitate repentance and returning to worship Allah Alone. Major polytheism condemns its perpetrator to Hellfire if he does not repent, and its examples include associating partners with Allah in worship and directing acts of worship to other than Allah such as sacrifice, vows, and supplication, and Allah says in Ayat (48,116) of Surat Alnisa' {Indeed, Allah does not forgive that to be associated with Him, but He forgives what is less than that for whom He wills}, and as narrated by Jabir bin Abdullah: "A man came to the Messenger of Allah and said Messenger of Allah! What are the two things quite unavoidable?, He replied whoever dies without associating anything with Allah would enter Paradise, and whoever dies associating anything with Allah would enter the Fire" (Sahih Muslim 93 a).
And as for the minor polytheism, it is a means to major polytheism and a way to fall into it, and all types of this polytheism revolves around hypocrisy, which means that a person performs an act of worship, not intending thereby to please Allah Alone, but rather to please people for some worldly gains. And in this Hadith, Allah's Messenger (PBUH) assures that Allah Almighty says He is the Most Self-Sufficient, and if a person performs an act of worship that belongs exclusively to Allah, and he makes it for Allah and for other than Allah, Allah will abandon him and will not accept it from him, nor will He give him any reward for it, so Allah does not accept except what is purely for His sake.
So hypocrisy nullifies good deeds, and it was called hidden polytheism because it resides in the human soul and it is only known to Allah, and the servant does reveal it to people, rather conceals it in his heart and rejoices in people's observation of his deeds, without intending to please Allah through his deeds, but Allah will reveal what is in his heart to people as Allah's Messenger (PBUH) said in narration of Jundab: "Whoever wants to be heard of, Allah will make him heard of, and whoever wants to be seen, Allah will show him i.e. expose his real motives" (Sunan Ibn Majah 4207).
Allah has threatened those who pray to show off their prayer to the people with destruction in the Hereafter in Aya (4-7) of Surat Alma'un, and Allah assures that the hypocrites will be in the lowest level of the Fire except for those who repent, and reform, and hold fast to Allah, and are sincere in their religion for Allah, then those will be with the believers and Allah will grant the believers a great reward as He has stated in Ayat (142-146) of Surat Alnisa'.
But if a servant performs an act purely for Allah, and then Allah instills good praise for him in the hearts of the believers and he rejoices by that, then that will not harm him, as Abu Dharr reported: "I said to the Prophet (PBUH) a man does a deed for the sake of Allah, and people love him for it, He said that is immediate glad tidings of the believer" (Sunan Ibn Majah 4225).