Salat must be dedicated to God alone

Every facet of our religious practices must be devoted to God alone.

[6:162] Say, "My Contact Prayers (Salat), my worship practices, my life and my death, are all devoted absolutely to GOD alone, the Lord of the universe.​قُلْ إِنَّ صَلَاتِى وَنُسُكِى وَمَحْيَاىَ وَمَمَاتِى لِلَّهِ رَبِّ ٱلْعَـٰلَمِينَ

[98:5] All that was asked of them was to worship GOD, devoting the religion absolutely to Him alone, observe the contact prayers (Salat), and give the obligatory charity (Zakat). Such is the perfect religion.

وَمَا أُمِرُوا إِلَّا لِيَعْبُدُوا اللَّهَ مُخْلِصِينَ لَهُ الدِّينَ حُنَفَاءَ وَيُقِيمُوا الصَّلَاةَ وَيُؤْتُوا الزَّكَاةَ وَذَٰلِكَ دِينُ الْقَيِّمَةِ

No other names should ever be mentioned in our Salat.

[39:45] When GOD ALONE is mentioned, the hearts of those who do not believe in the Hereafter shrink with aversion. But when others are mentioned beside Him, they become satisfied.

وَإِذَا ذُكِرَ ٱللَّهُ وَحْدَهُ ٱشْمَأَزَّتْ قُلُوبُ ٱلَّذِينَ لَا يُؤْمِنُونَ بِٱلْـَٔاخِرَةِ وَإِذَا ذُكِرَ ٱلَّذِينَ مِن دُونِهِۦٓ إِذَا هُمْ يَسْتَبْشِرُونَ

If anyone thinks that mentioning another name in their Salat will somehow bring them closer to God, either through Wasila (proximity) or Shafia (intercession), this is shirk (idol worship).

[1:5] You alone we worship; You alone we ask for help.

إِيَّاكَ نَعْبُدُ وَإِيَّاكَ نَسْتَعِينُ

[39:3] Absolutely, the religion shall be devoted to GOD alone. Those who set up idols beside Him say, "We idolize them only to bring us closer to GOD; for they are in a better position!" GOD will judge them regarding their disputes. GOD does not guide such liars, disbelievers.

أَلَا لِلَّهِ ٱلدِّينُ ٱلْخَالِصُ وَٱلَّذِينَ ٱتَّخَذُوا۟ مِن دُونِهِۦٓ أَوْلِيَآءَ مَا نَعْبُدُهُمْ إِلَّا لِيُقَرِّبُونَآ إِلَى ٱللَّهِ زُلْفَىٰٓ إِنَّ ٱللَّهَ يَحْكُمُ بَيْنَهُمْ فِى مَا هُمْ فِيهِ يَخْتَلِفُونَ إِنَّ ٱللَّهَ لَا يَهْدِى مَنْ هُوَ كَـٰذِبٌ كَفَّارٌ

[10:18] They worship beside GOD idols that possess no power to harm them or benefit them, and they say, "These are our intercessors at GOD!" Say, "Are you informing GOD of something He does not know in the heavens or the earth?" Be He glorified. He is the Most High; far above needing partners.

وَيَعْبُدُونَ مِن دُونِ ٱللَّهِ مَا لَا يَضُرُّهُمْ وَلَا يَنفَعُهُمْ وَيَقُولُونَ هَـٰٓؤُلَآءِ شُفَعَـٰٓؤُنَا عِندَ ٱللَّهِ قُلْ أَتُنَبِّـُٔونَ ٱللَّهَ بِمَا لَا يَعْلَمُ فِى ٱلسَّمَـٰوَٰتِ وَلَا فِى ٱلْأَرْضِ سُبْحَـٰنَهُۥ وَتَعَـٰلَىٰ عَمَّا يُشْرِكُونَ

[17:57] Even the idols that they implore are seeking the ways and means towards their Lord. They pray for His mercy, and fear His retribution. Surely, the retribution of your Lord is dreadful.

أُو۟لَـٰٓئِكَ ٱلَّذِينَ يَدْعُونَ يَبْتَغُونَ إِلَىٰ رَبِّهِمُ ٱلْوَسِيلَةَ أَيُّهُمْ أَقْرَبُ وَيَرْجُونَ رَحْمَتَهُۥ وَيَخَافُونَ عَذَابَهُۥٓ إِنَّ عَذَابَ رَبِّكَ كَانَ مَحْذُورًا

In theory, any place where we pray can be a place of worship, and God commands that we not call upon any other entity at any place of worship. Therefore, we should never call upon any other entity in any aspect of our worship.

[72:18] The places of worship belong to GOD; do not call on anyone else beside GOD.وَأَنَّ ٱلْمَسَـٰجِدَ لِلَّهِ فَلَا تَدْعُوا۟ مَعَ ٱللَّهِ أَحَدًا

Yet, Sunnis do just that in their tashahud when they call directly upon the prophet as if he is able to hear their prayers.

“Salutations to God and prayers and good deeds. Peace be upon you, O Prophet, as well as God’s mercy and His blessings. Peace be upon us and upon the righteous servants of God. I bear witness that there is no deity but God, and I bear witness that Muhammad is His servant and His messenger.”

​ٱلتَّحِيَّاتُ لِلَّٰهِ وَٱلصَّلَوَاتُ وَٱلطَّيِّبَاتُ، ٱلسَّلَامُ عَلَيْكَ أَيُّهَا ٱلنَّبِيُّ وَرَحْمَةُ ٱللَّٰهِ وَبَرَكَاتُهُ، ٱلسَّلَامُ عَلَيْنَا وَعَلَىٰ عِبَادِ ٱللَّٰهِ ٱلصَّالِحِينَ، أَشْهَدُ أَنْ لَا إِلَٰهَ إِلَّا ٱللَّٰهُ، وَأَشْهَدُ أَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ.

​at-taḥiyyātu li-llāhi, wa-ṣ-ṣalawātu wa-ṭ-ṭayyibātu. as-salāmu ʿalayka ʾayyuhā n-nabiyyu wa raḥmatu -llāhi wa barakātuhu. as-salāmu ʿalaynā wa ʿalā ʿibādi -llāhi ṣ-ṣāliḥīna. ʾashhadu ʾan lā ʾilāha ʾillā -llāhu wa ʾashhadu ʾanna muḥammadan ʿabduhu wa rasūluhū.

The use of “Peace be upon you, O Prophet” ( ٱلسَّلَامُ عَلَيْكَ أَيُّهَا ٱلنَّبِيُّ ) is a direct call upon the prophet of God, who is not only another entity beside God but also dead and incapable of hearing their supplications.