Zurah Ibn Ibraheem said that a man came to 'Umar, radiyAllaahu 'anhu
and said to him: "I have an old mother who is unable to go to answer
the call of nature, so I carry her on my back. I also help her perform
ablution while turning my face away from her (out of respect). Have I
fulfilled my duty towards her?" 'Umar radiyAllaahu 'anhu said: "No."
The man said: "Even though I carry her on my back and exert myself in
her service." Umar (radhi allahu anhu) said: "She used to do the same
for you (when you were young) while hoping that you will live, as for
you - you wait when she will go away (die)." [Birr-ul-Walidain, by Ibn
Jawzi]
Ibn 'Umar radiyAllaahu 'anhu saw a man carrying his mother going
around the Ka'bah in Tawaf (circumambulation) and he asked Ibn 'Umar
radiyAllaahu 'anhu: "Have I fulfilled my duty towards her?" Ibn 'Umar
replied: "Not even for one contraction! However, you have done good
and Allaah will reward you tremendously for the little that you could
do." [Al-Kabair, p.42]