لا صلاة لجار المسجد إلا في المسجد
"There is no prayer for the neighbour of the Masjid except in the Masjid." (Ad-Darqutni 1/420 no. 1537, 1538 and Al-Baihaqi 3/75 and Mustadrak no. 1/246)
was recorded by Imam Ahmad, Ad-Daraqutni, Al-Hakim, At-Tabarani, and Ad-Daylami — they all related this Hadeeth, with a weak chain. Ibn Hajar said, "It has no authentic chain even though it is well-known among the people." Scholars of Hadeeth consider this Hadeeth to be weak.
But suppose the Hadeeth to be authentic; it means, then, that there is no prayer that is complete for the neighbour of the Masjid except in the Masjid, because there are authentic Hadeeths that do show that a person's prayer is correct when he prays alone, but he is sinning if he has no acceptable excuse from the Shari'ah not to pray in congregation.
The congregational prayer in the Masjid is compulsory, we gather this ruling not from the Hadeeth in question, but from other authentic Hadeeths, such as the Prophet's (sallAllaahu `alayhi wa sallam) saying,
من سمع النداء فلم يأته فلا صلاة له إلا من عذر
"Whoever hears the call (to prayer) but does not come, then he has no prayer, unless he has an excuse." (Ibn Majah no. 793, Ad-Darqutni 1/420,421 and Mustadrak 2/245)
Recorded by Ibn Majah, Ad-Daraqutni, Ibn Hibban and Al-Hakim — its chain fulfils the conditions of Muslim.
Once, when a blind man sought permission from the Prophet (sallAllaahu `alayhi wa sallam) to pray at home and excused himself by saying that he had no one who could lead him to the Masjid, the Prophet (sallAllaahu `alayhi wa sallam) said to him,
هل تسمع النداء بالصلاة
"Do you hear the call to prayer?"
The man said, "Yes." The Prophet (sallAllaahu `alayhi wa sallam) said,
"Then answer it". Recorded by Muslim (no. 653) in his Sahih