After completing full ablution, one should face the Qiblah and say Allāhu Akbar.
مِفْتَاحُ الصَّلَاةِ الطُّهُورُ، وَتَحْرِيمُهَا التَّكْبِيرُ، وَتَحْلِيلُهَا التَّسْلِيمُ.
transalation:
The key to prayer is purification, its opening is the Takbīr, and its closing is the Taslīm.
(Sunan Abū Dāwūd, al-Tirmidhī, Ibn Mājah – authentic hadith)
And according to the following hadith, he should raise both his hands until they are level with his shoulders:
:عَنِ ابْنِ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَ
أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ إِذَا قَامَ إِلَى الصَّلَاةِ رَفَعَ يَدَيْهِ حَتَّى يَحَاذِيَ بِهِمَا مَنْكِبَيْهِ، ثُمَّ كَبَّرَ..
Transaltion:
From Ibn ʿUmar (may Allah be pleased with them both):
The Messenger of Allah (may Allah bless him and give him peace), when he stood for prayer, would raise his hands until they were level with his shoulders, then he said the Takbīr…
(Sahih al-Bukhari, Book of Adhān, Hadith no. 735; Sahih Muslim, Book of Prayer, Hadith no. 390)
عَن مَالِكِ بْنِ حُوَيْرِثٍ رضي الله عنه قَالَ: «أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا كَبَّرَ رَفَعَ يَدَيْهِ حَتَّى يُحَاذِيَ بِهِمَا أُذُنَيْهِ»
Translation:
From Mālik ibn Huwayrith (may Allah be pleased with him) who said:
When the Messenger of Allah (may Allah bless him and give him peace) said the Takbīr, he would raise his hands until they were level with his ears. (Sunan al-Nasā’ī, Book of Opening, Chapter on Raising the Hands to the Level of the Shoulders.
Hadith no. 879; Sunan Abū Dāwūd, Book of Prayer, Chapter on Raising the Hands in Prayer, Hadith no. 749)