I prayed with the Prophet ﷺ, and a man said, "Praise be to Allah, abundant, pure, and blessed praise."When the Prophet ﷺ finished the prayer, he asked, "Who said that?"The man replied, "I did, and I intended nothing but good by it."The Prophet ﷺ said, "The gates of heaven were opened for it, and nothing held it back until it reached the Throne."
حدثنا علي بن محمد حدثنا يحيى بن آدم حدثنا إسرائيل عن أبي إسحق
صليت مع النبي ﷺ فقال رجل الحمد لله حمدا كثيرا طيبا مباركا فيه فلما صلى النبي ﷺ قال من ذا الذي قال هذا قال الرجل أنا وما أردت إلا الخير فقال لقد فتحت لها أبواب السماء فما نهنهها شيء دون العرش
[Its chain of transmission is daif] Nasai narrated it, 2/145, 146, Al-Iftitah, "What the one being led in prayer should say if he sneezes behind the imam," no. 933, from the hadith of Abu Ishaq, with this wording. Ahmad also narrated it, 4/317, from Yahya bin Adam, with this wording.It has corroborating narrations. Abdul-Jabbar did not hear from his father, as mentioned previously at no. 855, so the chain is disconnected, but the basic content of the hadith is sahih, being supported by very many corroborations.