Reference : Hisn al-Muslim 221

وَقَالَ صلى الله عليه وسلم: (الْبَخِيلُ مَنْ ذُكِرْتُ عِنْدَهُ فَلَمْ يُصَلِّ عَلَيَّ)
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The Prophet (ﷺ) said: "The miser is the one in whose presence I am mentioned yet does not pray for Allah's blessings upon me."

Reference:
At-Tirmidhi 5/551 and others. See also Al-Albani, Sahih At-Tirmidhi 3/177 
and Sahihul-Jarai' As-Saghir 3/25.

Chapter: Excellence of sending prayers upon the Prophet (saws)