Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
suyuti:9631a

"O you who are praying alone, why don't you join them and enter with them, or bring someone to stand beside you if the place becomes tight for you? Repeat your prayer, for indeed, there is no prayer for you."  

السيوطي:٩٦٣١a

"أَيُّهَا الْمُصَلِّي وَحْدَه أَلَا وَصَلتَ إِلَى الصَّفِّ فَدَخَلتَ مَعَهُمْ، أَو جَرَرْتَ إِلَيكَ رَجُلًا إِن ضَاقَ بِك الْمَكَانُ فَقَامَ مَعَكَ أَعِدْ صَلاتَكَ فإنَّهُ لَا صَلاة لَكَ ".  

[طب] الطبرانى في الكبير [ع] أبو يعلى والشيرازى في الأَلقاب عن وابصة بن معبد (أَنه ﷺ قال لرجل صلى خلف الصف: أَيُّهَا المصلى وذكره، ورواه البيهقي أَيضًا وقال إِسناده ضعيف)

See similar narrations below:

Collected by Ṭabarānī, Suyūṭī

Pulling someone from the last row to have at least two people in a row when joining a congregational prayer

tabarani:18688Aḥmad b. Yaḥyá b. Khālid b. Ḥayyān al-Raqqī > Abū ʿUbaydah b. Fuḍayl b. ʿIyāḍ > Mālik b. Suʿayr > al-Sarī b. Ismāʿīl > al-Shaʿbī > Wābiṣah b. Maʿbad

The Messenger of Allah ﷺ left and there was a man praying alone behind the people. He said, "O you who are praying alone, why don't you join them and enter with them, or bring someone to stand beside you if the place becomes tight for you? Repeat your prayer, for indeed, there is no prayer for you."  

الطبراني:١٨٦٨٨حَدَّثَنَا أَحْمَدُ بْنُ يَحْيَى بْنُ خَالِدِ بْنِ حَيَّانَ الرَّقِّيُّ ثنا أَبُو عُبَيْدَةَ بْنُ فُضَيْلِ بْنِ عِيَاضٍ ثنا مَالِكُ بْنُ سُعَيْرٍ ثنا السَّرِيُّ بْنُ إِسْمَاعِيلَ عَنِ الشَّعْبِيِّ عَنْ وَابِصَةَ بْنِ مَعْبَدٍ قَالَ

انْصَرَفَ رَسُولُ اللهِ ﷺ وَرَجُلٌ يُصَلِّي خَلْفَ الْقَوْمِ وَحْدَهُ فَقَالَ «أَيُّهَا الْمُصَلِّي وَحْدَهُ أَلَا تَكُونَ وَصَلْتَ صَفًّا فَدَخَلْتَ مَعَهُمْ أَوِ اجْتَرَرْتَ رَجُلًا إِلَيْكَ إِنْ ضَاقَ بِكَ الْمَكَانُ أَعِدْ صَلَاتَكَ فَإِنَّهُ لَا صَلَاةَ لَكَ»  

Pulling someone when encountering a full row in a congregational prayer

suyuti:1406aIbn ʿAbbās

"When one of you encounters a complete row, let him call a man to stand next to him."  

السيوطي:١٤٠٦aعن ابن عباس

"إِذَا انْتهَى أحدُكم إلى الصّفِّ وقدْ تَمَّ فْليجذْب إليه رَجُلًا يُقيمه إلى جنْبِه".  

[طس] الطبرانى في الأوسط عن ابن عباس