Question: Is the hadîth, “Whoever is for Allah, Allah is for him,” which is written in Forty Ahâdîth by Sadraddîn Konawî, authentic?
ANSWER
Asking this is much absurder than having an elementary child check a mathematical operation done by a professor of mathematics. Did Hadrat Sadraddin Konawî not have as much knowledge as we have? Was he so heedless and ignorant as to report a made-up hadîth in his book? The meaning of this hadîth-i sharîf is as follows:
(Whoever’s objective is the pleasure of Allah, Allahu ta’âlâ will make him attain to his objective.)

There are similar verses in the Qur’ân al-karîm. Some of them are as follows:
(Allah is pleased with those who fear [who avoid sins] their Rabb [He accepts their acts of worship. That is how he is pleased with them], and they are pleased with Him [because they have attained more than they expect].) [Sûrat-ul-Bayyinah, 8]

(Remember Me, and I will remember you.) [Sûrat-ul-Baqara, 152]

That is, if you remember Me through acts of worship, I will remember you with compassion. If you pray to Me, I will respond to your prayer. If you remember Me in the world, I will remember you in the Hereafter. If you remember Me in times of ease and comfort, I will remember and help you in times of distress.

(If you help Allah, He will help you.) [Sûrat-u Muhammad, 7]

That is, if you strive to serve Allah’s religion, Allah, in turn, will help you against your enemies.

(Allah helps those who help Him.) [Sûrat-ul-Hajj, 40]
Helping Allah means serving His religion. In other words, Allah is the helper of those who work for the cause of Him. He multiplies His rewards in return for His slave’s a little effort. For a single good deed, He grants a tenfold recompense or seven hundredfold recompense or even more than this. (Sûrat-ul-Baqara, 261)

There are many hadîth-i qudsîs on this subject. Some of them are as follows:
(I will be the eyes which see, the ears which hear, the hands which hold things, the feet which walk, the tongue which talk, of My born servant I like. I will give him whatever he wants.) [Bayhaqî]

(Whoever approaches Me by the length of a hand-span, I will approach him by a cubit. Whoever approaches Me by a cubit, I will approach him by the length of two outstretched arms. If anyone comes to Me walking, I will approach him running.) [Bukhârî, Imam-i Ahmad, Ibni Shâhin]

(Remember Me with My tâ'at, and I will remember you with My forgiveness. Whoever remembers Me obediently, I will forgive him. Whoever remembers Me disobediently, I will remember him with My torment.) [Daylamî]

(You are grateful as long as you remember Me. You are in disbelief [that is, you are ungrateful] as long as you forget Me.) [Hatib]

(If a person remembers Me in private, I will remember him near angels. If a person remembers Me at a gathering, I will remember him at a gathering which is better and bigger than that one.) [Tabarânî]

(O son of Âdam! When you get angry, remember Me. In this way, when I become angry, I will remember you with My forgiveness and will not destroy you among those who will be destroyed.) [Ibni Shâhin]

(I am with My slave as long as his lips are moving with My dhikr [remembrance].) [Bukhârî]