Hadith: Indeed, patience is at the first shock

عن أنس بن مالك رضي الله عنه قال: مرَّ النَّبي - صلى الله عليه وسلم - بامرَأَة تَبكِي عِند قَبرٍ، فقال: «اتَّقِي الله واصْبِري» فقالت: إليك عَنِّي؛ فَإِنَّك لم تُصَب بِمُصِيبَتِي ولم تَعرِفه، فقِيل لها: إِنَّه النَّبِي - صلى الله عليه وسلم - فأتت باب النبي - صلى الله عليه وسلم - فلم تجد عنده بوَّابِين، فقالت: لم أَعرِفكَ، فقال: «إِنَّما الصَّبرُ عِند الصَّدمَةِ الأُولَى». وفي رواية: «تَبكِي على صبِّي لها».
[صحيح] - [متفق عليه]

Anas ibn Mālik (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) passed by a woman who was weeping beside a grave. He said to her: "Fear Allah and be patient." She said to him: "Leave me alone, for you have not been afflicted with a calamity like mine." She did not recognize him. She was later informed that he was the Prophet (may Allah's peace and blessings be upon him). So, she went to his house and there she did not find any doormen. Then she said to him: "I did not recognize you." He said: "Indeed, patience is at the first shock." According to another narration: "She was crying over a son of hers.”
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

The Prophet (may Allah's peace and blessings be upon him) passed by a woman at the grave of her son who had died. She used to love him dearly and could not keep herself from going out to his grave and crying there. When the Prophet (may Allah's peace and blessings be upon him) saw her, he commanded her to fear Allah and be patient. She said: "Leave me alone, for you have not been afflicted with a calamity like mine." Then, it was said to her that this man was the Messenger of Allah (may Allah's peace and blessings be upon him). So, she felt regret and went to the door of the Messenger of Allah (may Allah's peace and blessings be upon him) where there were no doormen to prevent people from entering. She said: "I did not recognize you." The Prophet (may Allah's peace and blessings be upon him) then informed her that true patience, which one is rewarded for, is what he shows at the first strike of a calamity.