Invocation for someone who tells you: :
أُحِبُّك لِلَّهِ "I love you for the
sake of Allah"
أَحَبَّـكَ الّذي أَحْبَبْـتَني لَه
200. 'Ahabbakal-lathee 'ahbabtanee lahu.
May He
for Whose sake you love me, love you.
Reference: Abu Dawud
4/333. Al-Albani graded it good in Sahih Abu Dawud 3/965.