يُعَدُّ كِتَابُ مَعْرِفَة الصَّحَابَةِ (الْمَفْقُودِ) لابْنِ السَّكَن (المتوفى: 353هـ) مِنْ أَهَمِ أُمَّهَاتِ كُتُبِ الصَّحَابةِ وأقدمها تصنيفًا، فَمَا مِنْ أَحدٍ صَنَّفَ بَعدَهُ في الصَّحَابةِ إِلَا وقد نَقَلَ وَأَفَادَ مِنْ هَذَا السِّفْرِ العظيم، واسْتَشْهَدَ وَاحْتَجَّ بِهِ أَئِمَّةُ هَذَا الفَنِ كَأَمْثَالِ: أَبُو عُمَرَ بْنُ عَبْدِ البَّر فِي كِتَابِهِ الاسْتِيعَابِ، وابْنُ الأَثِيرِ فِي أُسْدِ الغَابَة، وابْنُ حَجَرٍ العَسْقَلانِيّ فِي الإِصَابَةِ وغيرهم كثير، وَأَمَا عَنْ إِحْصَاءِ مَا اقْتَبَاسَهُ ابْنِ حَجَرٍ العَسْقَلانِيّ فِي الإِصَابَةِ مِنْ كِتَابِ مَعْرِفَةُ الصَّحَابَةِ لابْنِ السَّكَنِ فَيُعَدُّ بمئات الْمَرْوَيَّاتِ، واحْتَجَّ بِأَقوالِهِ كَثِيراً، وَأَفَاد مِنْ مَنْهَجِهِ مَا لَا يُعَدُّ وَلَا يُحْصَى؛ لِذَا وَقَعَ الاخْتِيارُ عَلَى مُصَنَفِهِ لِتَكْوينَ جُزءٍ هَامٍ مِنْ كِتَابِ مَعْرِفَة الصَّحَابَةِ لابْنِ السَّكَنِ وَهِي المَرْوِيَّات التي عَلَيْهَا الْمُعَوَّلُ في إِثْبَاتِ الصَّحبةِ، والتَّرجِيح عِنْدَ الاخْتِلافِ فِيهَا، وإثبات الْمُرْسَل وَالْمَوْصُول، وغيرها من الفوائد التَّاريخية الحديثية العزيزة المنال، فجاء البَحثُ على قسمين، الأول: التَّعْرِيفِ بابْنِ السَّكَنِ وكِتَابِه مَعْرِفَةِ الصَّحَابَةِ، وَبَيان أَهْمِيتِهُ التَّارِيخِية وَمَنْهَجِهُ، والثاني: تَكْوِينُ صُوَرة لتَرَاجِمِ الصَّحَابَةِ الْمُنْتَقَاةُ مِنْ كِتَابِ الإِصَابَةِ لِلحَافِظِ ابْنِ حَجَرٍ مِمَّنْ ذَكَرَهُم ابْنُ السَّكَنِ فِي كِتَابِ مَعْرِفَةِ الصَّحَابَةِ، وتوصّلت الدِّرَاسَةُ لِمَجْمُوعَةٍ من النتائج والإحصائيات والتّوصيات الجديرة بالذكر تضمنتها الخاتمة، أرجو من الله أن يَفْتَحَ بها الْمُسَتغلق، ويَجْمَعَ به المتفرق البعيد، وَيَنْفَعَ بِهَا العِلم والعُلَمَاء. Abstract  The Book of Knowing the Companions (The Lost) wrote by Ibn al-Sakan (died 353 AH) is considered one of the most important and oldest books of the Companions and the oldest in its classification. There was no one who was classified among the Companions after him except that he had transmitted and benefited from this great book. It was cited and used as evidence by the imams of this art، such as: Abu Omar bin Abdul-Barr in his book Al-Isti'ab، Ibn Al-Atheer in Asad Al-Ghabah، and Ibn Hajar Al-Asqalani in Al-Isaba and many others. As for counting what Ibn Hajar Al-Asqalani quoted in Al-Isaba from Ibn Al-Sakan's book “Ma'rifat al-Sahaba" (Knowing the Companions)، it is numbered in hundreds of narrations، He used many of his statements as evidence، and his approach benefited countless people. Therefore، his work was chosen to compose an important part of the book “Ma'rifat al-Sahaba" by Ibn al-Sakan، which are the narrations that are relied upon in proving companionship، Proof of what is sent and what is delivered، and other historical and modern benefits that are dear to us. The research was divided into two parts، the first: introducing Ibn al-Sakan and his book، Knowledge of the Companions، and explaining its historical importance and approach، The second: Compiling a picture of the biographies of the Companions selected from the book Al-Isabah by Al-Hafiz Ibn Hajar، among those whom Ibn Al-Sakan mentioned in his book “Ma'rifat Al-Sahab". The study reached a set of noteworthy results، statistics، and recommendations included in the conclusion، I hope that allah will open up the closed، and bring together the scattered، and benefit knowledge and scholars through it.