Kitāb al-Ghayba > Concealed Birth of the Imam of the Time (a.s) was not an extraordinary event
Hadith #9

قلنا: ليس الأمر على ما قلتم، لأن الإمامية تقول إن جماعة من أصحاب أبي محمد الحسن بن علي عليه السلام قد شاهدوا وجوده في حياته وكانوا أصحابه وخاصته بعد وفاته والوسائط بينه وبين شيعته معروفون، ربما ذكرناهم فيما بعد، ينقلون إلى شيعته معالم الدين ويخرجون إليهم أجوبته في مسائلهم فيه ويقبضون منهم حقوقه وهم جماعة كان الحسن بن علي عليهما السلام عد لهم في حياته واختصهم أمناء له في وقته وجعل إليهم النظر في أملاكه والقيام بأموره بأسمائهم وأنسابهم وأعيانهم،كأبي عمرو عثمان بن سعيد السمان وابنه أبي جعفر محمد بن عثمان بن سعيد وغيرهم ممن سنذكر أخبارهم فيما بعد إن شاء الله تعالى. وكانوا أهل عقل وأمانة وثقة ظاهرة ودراية وفهم وتحصيل ونباهة،وكانوا معظمين عند سلطان الوقت لعظم أقدارهم وجلالة محلهم مكرمين لظاهر أمانتهم واشتهار عدالتهم حتى أنه كان يدفع عنهم ما يضيفه إليهم خصومهم. وهذا يسقط قولهم أن صاحبكم لم يره أحد ودعواهم خلافه.

We will say: The case is not as suggested. A number of the companions of Abu Muhammad Hasan Ibn Ali (a.s) saw him during the lifetime of his father and they were his companions and close devotees after his father’s demise. They were middlemen between him and his Shia and were well known, as we have narrated, and carried religious guidance to the Shia and brought his answers to their questions and received their religious dues from them for him. They were persons, who were declared righteous by Hasan Ibn Ali (a.s) in his lifetime and he had appointed them his trustees and had designated them with overseeing his properties and his affairs, mentioning them by their names and names of their fathers such as Abu Amr Uthman Ibn Saeed Samman, his son Abu Ja’far Muhammad Ibn Uthman Ibn Saeed, and others that we will mention in detail soon. They were wise, trustworthy, extremely reliable and intelligent and men of great, noble character. They were respected by the rulers of the time for their nobility and majesty, and honored for their trustworthiness and famed lofty characters. They were so trustworthy that they would return even their enemies’ trusts. This invalidates the assertion that no one has seen our master.