Sayyiduna Ibn Umar (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "O Allah, have mercy on those who shave their heads." They said: "And those who shorten their hair?" He (peace and blessings be upon him) said: "O Allah, have mercy on those who shave their heads!" They said: "And those who shorten their hair too?" He (peace and blessings be upon him) said: "And those who shorten their hair too."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9396
(a) Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that the Prophet (peace and blessings be upon him) and a group of his Companions shaved their heads, and some had their hair cut short. Sayyiduna Ibn Umar (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "May Allah have mercy on those who shave their heads," once or twice, then he said: "And on those who cut their hair short too."
(b) In another narration, also from Sayyiduna Ibn Umar (may Allah be pleased with them both), he said the fourth time: "And on those who cut their hair short."
(c) In one narration of Sayyiduna Abu Hurayrah (may Allah be pleased with him), he said the third time: "And on those who cut their hair short."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9397
Yahya bin Husayn narrates from his grandmother (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) supplicated three times for those who shaved their heads and once for those who cut their hair short.
The Shaykh said: His grandmother was Umm Husayn al-Ahmasiyyah (may Allah be pleased with her).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9398