Hadith 1: Dont be a Ghali and dont be a Muqassir

Narrated that Prophet Muhammad (صلى الله عليه وآله) said as part of a hadith regarding Imam Ali (عليه السلام):

وسيهلك فيه اثنان ولا ذنب له: محب غال, ومقصر

"Regarding Him two groups of people will be destroyed - for no fault of His - an exaggerating lover (Ghali) and the one who falls short/reduces/lessens His rights (Muqassir)."

[Source: al-Amali, Shaikh Sadooq, Pg. 264]

Hadith 2: Who is a Ghali?

Part of a hadith as narrated from Abu Jafar Imam Baqir (عليه السلام):

 حُمَيْدُ بْنُ زِيَادٍ عَنِ الْحَسَنِ بْنِ مُحَمَّدِ بْنِ سَمَاعَةَ عَنْ بَعْضِ أَصْحَابِهِ عَنْ أَبَانٍ عَنْ عَمْرِو بْنِ خَالِدٍ عَنْ أَبِي جَعْفَرٍ (عَلَيهِ السَّلام) ...

 فَقَالَ لَهُ رَجُلٌ مِنَ الأنْصَارِ يُقَالُ لَهُ سَعْدٌ جُعِلْتُ فِدَاكَ مَا الْغَالِي قَالَ قَوْمٌ يَقُولُونَ فِينَا مَا لا نَقُولُهُ فِي أَنْفُسِنَا فَلَيْسَ أُولَئِكَ مِنَّا وَلَسْنَا مِنْهُمْ

A person from the Ansar (people of Medina) whose name was said to be Sa'd, said to the Imam, "May I be sacrificed for You, Who is a 'Ghali' ?

Imam (عليه السلام) said, "They are the people who say about Us what We do not say about Ourselves. So, they are not from Us and We are not from them."

[Source: al-Kafi, Vol. 2, Pg. 75] 

Hadith 3: Be Balanced

مُحَمَّدُ بْنُ خَالِدٍ الطَّيَالِسِيُّ، عَنْ فَضْلِ بْنِ عُثْمَانَ عَنْ أَبِي عَبْدِ اللَّهِ عَلَيْهِ السَّلَامُ قَالَ: «اتَّقُوا اللَّهَ، وَ عَظِّمُوا اللَّهَ، وَ عَظِّمُوا رَسُولَهُ، وَ لَا تُفَضِّلُوا عَلَى رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَ آلِهِ وَ سَلَّمَ أَحَداً، فَإِنَّ اللَّهَ تَبَارَكَ وَ تَعَالَى قَدْ فَضَّلَهُ. وَ أَحِبُّوا أَهْلَ بَيْتِ نَبِيِّكُمْ حُبّاً مُقْتَصِداً، وَ لَا تَغْلُوا، وَ لَا تَفَرَّقُوا، وَ لَا تَقُولُوا مَا لَا نَقُولُ، فَإِنَّكُمْ إِنْ قُلْتُمْ وَ قُلْنَا بَعَثَكُمُ اللَّهُ وَ بَعَثَنَا وَ كُنَّا حَيْثُ يَشَاءُ اللَّهُ وَ كُنْتُمْ»

Narrated that Abu Abdillah Imam Sadiq (عليه السلام) said:

"Fear Allah, exalt Allah, and exalt His Messenger. Do not prefer anyone over the Messenger of Allah (صلى الله عليه وآله), for indeed Allah (تبارك وتعالى) has preferred him.

And love the Ahl al-Bayt of your Prophet with a moderate love [i.e. taking a middle course]. And do not go to extremes (ghulv), do not be divided, and do not say what we do not say.

For if you say and we say, Allah will resurrect you and resurrect us, and we will be where Allah wills, and so will you be."

[Source: Qurb al-Asnad, Pg. 159]