There are eight duties a Muslim must obey to in prayers, like the glorification. And if they are deliberately omitted, the prayer is invalid. If it is forgotten, it is compensated for by two prostrations at the end. 

Duties in prayer

Nine duties (obligatory acts) must be observed in prayer, and if they are deliberately omitted, the prayer is invalid. If any is forgotten, it is compensated for by two prostrations at the end of prayer. If they are omitted out of ignorance, the prayer is valid. These eight duties are as follows:

1-All the glorifications (takbeer), i.e. Allah-u akbar, other than the initial one that is for consecration. These are called the glorification of moving on.

The Prophet (peace be upon him) continued to do so throughout his life and he ordered us to pray in the same way he prayed.

2- The imam leading the prayer and a person praying alone says sami'a Allah liman hamidah (i.e. ‘may Allah answer the prayer of the one who praises Him’) when standing up after bowing.

3-Every worshipper in the congregation says only Rabbana wa lak alhamd, while the imam leading the prayer and a person praying alone says it after saying sami'a Allah liman hamidah. This is clear in the above-quoted hadith reported by Abu Hurayrah, and in the other hadith reported by Abu Musa in which he quotes the Prophet (peace be upon him) saying:

4-When bowing, one should say subhana Rabbiy A’theem, which means ‘I praise my Lord the great and exonerate Him from any fault or defect’. The duty is to say it at least once.

5-In prostration one should say subhana Rabbiy al-a'la, which means “I praise my Lord the most high and exonerate Him from any fault or defect”.

It is recommended to say these glorifications at least three times in each bowing and prostration.

6-When sitting between the two prostrations one should say Rabb ighfir li, i.e. ‘My Lord, forgive me.

7-The first tashahhud, except for people in the congregation when the imam forgets this tashahhud and rises for the next rak'ah. Those in the congregation are exempt from it because they have an overriding obligation to follow the imam. When the Prophet (peace be upon him) forgot this tashahhud he did not go back to perform it.

 This tashahhud requires saying: Al-tahiyyatu lillah, was-salawatu wat-tiyyibat. Assalamu 'alayka ayyuha-nnabiyyu wa rahmatullahi wa barakatuh. Assalamu ' alayna wa 'ala 'ibadi-llahis-salihin. Ashhadu an la ilah illa Allah, wa ashhadu anna Muhammad-an 'abduhu wa rasuluh. This means: ‘Greetings are offered to Allah, and blessings and all good things belong to Him. Peace be to you, Prophet (peace be upon him), with Allah’s grace and blessings. Peace be to us and to all good servants of Allah. I bear witness that there is no deity other than God, and I bear witness that Muhammad is His servant and messenger.

8-To sit down for this first tashahhud, as stated in the hadith reported by Ibn Mas'ud, quoting the Prophet (peace be upon him) :

Another hadith reported by Rifa'ah ibn Rafi'  quotes the Prophet as saying:

9. The salutation upon the Prophet (peace be upon him) (salla Allahu alaihi wa sallam) in the last rak’ah known as Assalatul Ibrahimiyah.