Here is a Ṣaḥīḥ (Authentic) ḥadīth that the great companion Ṣafwān b. Mihrān al-Jammāl saw Imām al-Ṣādiq (عليه السلام) after his prayer raised his hands together above his head.
I have already posted some supplications that are authentic to read after your obligatory salāh (click here). I have also already posted Ṣaḥīḥ (Authentic) ḥadīth that says when you do du`ā’. you raise your hands (click here).
الْحُسَيْنُ بْنُ سَعِيد عَنِ ابْنِ أَبِي نَجْرَانَ عَنْ صَفْوَانَ بْنِ مِهْرَانَ الْجَمَّالِ قَالَ رَأَيْتُ أَبَا عَبْدِ اللَّهِ ع إِذَا صَلَّى فَفَرَغَ مِنْ صَلَاتِهِ رَفَعَ يَدَيْهِ جَمِيعاً فَوْقَ رَأْسِهِ
(al-Ṭūsī’s chain of narrators to[1]) al-Ḥussayn b. Sa`īd[2] from Ibn Abī Najrān[3] from Ṣafwān b. Mihrān al-Jammāl[4] said, “I saw Abā `Abd Allāh (عليه السلام) when he finished from his salāh he raised his hands together above his head”[5]
[1] al-Khoei says that the tarīq (path) from al-Ṭūsī to al-Ḥussayn b. Sa`īd al-Ahwāzī is Ṣaḥīḥ (Authentic) (See: al-Khoei, Mu`jam Rijāl al-Hadīth, vol. 6, pg. 265-291)
[2] al-Ḥussayn b. Sa`īd b. Hammād is thiqah (trustworthy) according to al-Ṭūsī (See: al-Ṭūsī, al-Fihrist, pg. 149-150, person # 230 & al-Ṭūsī, al-Rijāl, pg. 355, person # 5257), and al-Ḥillī (See: al-Ḥillī’s al-Khulāṣah, pg. 39, person # 3).
[3] `Abd al-Raḥmān b. Abī Najrān is thiqah (trustworthy) according to al-Najāshī (See: al-Najāshī, al-Rijāl, pg. 235-236, person # 622) and al-Ḥillī (See: al-Ḥillī’s al-Khulāṣah, pg. 114, person # 7).
[4] Ṣafwān b. Mihrān b. al-Mughīrah al-Jammāl is thiqah (trustworthy) according to al-Najāshī (See: al-Najāshī, al-Rijāl, pg. 198, person # 525) and al-Ḥillī (See: al-Ḥillī’s al-Khulāṣah, pg. 89, person # 2).
[5] Al-Ṭūsī, Tahdīb al-Aḥkām, vol. 2, pg. 106, ḥadīth # 171; al-Majlisī said this ḥadīth is Ṣaḥīḥ (Authentic) (See: al-Majlisī, Milādh al-Akhyār, vol. 3, pg. 613)
Bibliography
al-Ḥillī. al-Khulāṣah al-`Aqwāl. 1st ed. 1 vols. Qum: , Dār al-Dukhā’ir, 1411.
al-Khoei. Mu`jam Rijāl al-Hadīth. 5th. 24 vols. 1413.
al-Majlisī. Milādh al-Akhyār. 1st. 16 vols. Qum: Maktabah Ayatollah al-Mar`ashī al-Najafī, 1406.
al-Najāshī. Rijāl. Ed. Musa al-Shabiri al-Zanjani. 5. 1 vols. Qum: Mu’assasah al-Nashr al-Islāmī, 1416.
al-Ṭūsī. al-Fihrist. Najaf: al-Maktabah al-Raḍawiyyah, n.d.
—. al-Rijāl. 1st. Qum: Mu’assasah al-Nashr al-Islāmī, 1415.
—. Tahdhīb al-Aḥkām. 4th. 10 vols. Tehran: Dār al-Kutub al-Islāmiyyah, 1407.