The Ruling on saying:"Verily, Allah is with the patient ones" by Those Who enter while the Imam is bowing

Question :

Is it permissible for a man who came to the prayer while the people are bowing, and he wanted to catch the bowing, to say: "Be patient, for verily, Allah is with the patient ones," addressing the Imam in a loud voice?

Answer:

This should not be done, whether he says: "Be patient, for verily, Allah is with the patient ones" or to clear one's throat, or to bang on the floor with one's foot or any such like action in order to inform the Imam that he has entered. He should enter quietly and calmly, without haste, according to the Hadith of the Prophet:
When you hear the Iqamah, then walk to the prayer and do not hurry, and whatever you catch of the prayer, pray it, then whatever you missed, complete it.

This Hadith, or its meaning, oblige you to come to prayer calmly, to join the row and pray with the Imam. Whatever you catch you should pray, and whatever you miss, you should make up for it. This is what the Prophet ordered. As for this annoyance and irritation to the Imam and the worshippers, it is an innovation that was not practiced in the time of the Companions, may Allah be pleased with them, and it should not be done.

Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 2 Pages 242-243