(25:6) Say, [O Muhammad], “It has been revealed by He who knows [every] secret within the heavens and the earth. Indeed, He is ever Forgiving and Merciful.”
Muhammad Taqi-ud-Din al-Hilali and Muhammad Muhsin Khan,
(25:6) Say: “It (this Quran) has been sent down by Him (Allah) (the Real Lord of the heavens and earth) Who knows the secret of the heavens and the earth. Truly, He is Oft-Forgiving, Most Merciful.”
Mohammed Marmaduke William Pickthall
(25:6) Say (unto them, O Muhammad): He who knoweth the secret of the heavens and the earth hath revealed it. Lo! He ever is Forgiving, Merciful.
Abdullah Yusuf Ali
(25:6) Say: “The (Qur’an) was sent down by Him who knows the mystery (that is) in the heavens and the earth: verily He is Oft-Forgiving, Most Merciful.”
Mohammad Habib Shakir
(25:6) Say: He has revealed it Who knows the secret in the heavens and the earth; surely He is ever Forgiving, Merciful.
Dr. Ghali
(25:6) Say, “He has sent it down, (He) who knows the secret in the heavens and the earth; surely He has been Ever-Forgiving, Ever-Merciful.”
Ali Unal
(25:6) Say: “(It is a Book full of knowledge revealing many secrets such as no human being could in any wise discover by himself:) He Who knows all the secrets contained in the heavens and the earth sends it down (to teach you some of these secrets and guide you in your life so that you may attain happiness in both worlds). He surely is All-Forgiving, All-Compassionate.”
Amatul Rahman Omar
(25:6) Say, `He Who knows every secret of the heavens and the earth has revealed this (Qur´ân). Verily, He is Great Protector, Ever Merciful.´
Literal
(25:6) Say: “Who knows the secret in the skies/space and the earth/Planet Earth descended it, that He truly is/was forgiving, merciful.”
Ahmed Ali
(25:6) Say: “He who knows the secrets of the heavens and the earth has revealed it to me; and He is surely forgiving and kind.”
A. J. Arberry
(25:6) Say: ‘He sent it down, who knows the secret in the heavens and earth; He is All-forgiving, All-compassionate.’
Abdul Majid Daryabadi
(25:6) Say thou; He hath sent it down Who knoweth the secret of the heavens and the earth; verily He is ever Forgiving, Merciful.
Maulana Mohammad Ali
(25:6)-
Muhammad Sarwar
(25:6) (Muhammad), tell them, “The One who knows all the secrets of the heavens and the earth has revealed it; He is All-forgiving and All-merciful.”
Hamid Abdul Aziz
(25:6) And they say, “Old folks´ tales, which he has written down while they are dictated to him morning and evening.”
Faridul Haque
(25:6) Proclaim (O dear Prophet Mohammed – peace and blessings be upon him), It is sent down by Him Who knows all the secrets of the heavens and the earth
Talal Itani
(25:6) Say, It was revealed by He who knows the Secret in the heavens and the earth. He is always Forgiving and Merciful.
Ahmed Raza Khan
(25:6) Proclaim (O dear Prophet Mohammed peace and blessings be upon him), It is sent down by Him Who knows all the secrets of the heavens and the earth; indeed He Oft Forgiving, Most Merciful.”
Wahiduddin Khan
(25:6) Say to them, “It has been revealed by Him who knows every secret that is in the heavens and on the earth. Truly, He is most forgiving and most merciful.”
Safi-ur-Rahman al-Mubarakpuri
(25:6) Say: “It has been sent down by Him Who knows the secret of the heavens and the earth. Truly, He is Oft-Forgiving, Most Merciful.”
Ali Quli Qarai
(25:6) Say, It has been sent down by Him who knows the hidden in the heavens and the earth. Indeed He is all-forgiving, all-merciful.
Hasan al-Fatih Qaribullah and Ahmad Darwish
(25:6) Say: ‘It was sent down by Him who knows the secrets of heavens and earth. He is Forgiving, the Most Merciful.
That is translated surah Al Furqan ayat 6 (QS 25: 6) in arabic and english text, may be useful.