What you have read is not correct. The correct view is that the man may be intimate with his wife when she is menstruating in all ways apart from intercourse.
The evidence for that has already been explained in the answer to question no. 36722.
Many of the scholars were of the view that it is haraam for a man to be intimate with his wife during her menses with regard to the area between the navel and the knees, and they quoted evidence for that, but this view has some flaws, for example :
1 – The report narrated by Abu Dawood (213) from Mu’aadh ibn Jabal who said: “I asked the Messenger of Allaah (peace and blessings of Allaah be upon him) what it is permissible for a man to do with his wife when she is menstruating. He said, ‘Whatever is above the izaar (waist wrapper), but refraining from that is better.’”
This hadeeth is da’eef, and was not proven from the Prophet (peace and blessings of Allaah be upon him).
Abu Dawood said: It is not strong. It was classed as da’eef by al-‘Iraaqi as it says in ‘Awn al-Ma’bood. And it was classed as da’eef by al-Albaani in Da’eef Abi Dawood, 36.
2 – Ahmad (87) narrated from ‘Umar ibn al-Khattaab that he asked the Prophet (peace and blessings of Allaah be upon him), “What can a man do with his wife when she is menstruating?” The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Whatever is above the izaar.”
Ahmad Shaakir said in Tahqeeq al-Musnad (86): its isnaad is da’eef (weak) because there is a missing link in it.
3 – Abu Dawood (212) also narrated from Haraam ibn Hakeem that his paternal uncle asked the Messenger of Allaah (peace and blessings of Allaah be upon him), “What is it permissible for me to do with my wife when she is menstruating?” He said, “Whatever is above the izaar.”
The scholars differed concerning this hadeeth. Ibn al-Qayyim narrated in Tahdheeb al-Sunan that some of the huffaaz regarded it as da’eef, and he concurred with that. It was classed as saheeh by al-Albaani in Saheeh Abi Dawood, 197.
Even if the hadeeth is saheeh, it does not constitute evidence that this is not permissible to engage in intimacy between the navel and the knees, because it is possible to reconcile between this hadeeth and other ahaadeeth which state that such intimacy is possible in one of the following ways:
1-It means that this is mustahabb to avoid the site of menstruation, not that it is obligatory to do so.
2-It may be interpreted as applying to the one who is not able to control himself, because if he is allowed to be intimate with the area between the thighs, for example, he may not be able to control himself and may have intercourse in the vagina, so he would be doing something haraam, either because he is lacking in religious commitment, or because his desire is too strong. So the ahaadeeth which indicate that it is permissible apply to the one who can control himself and the ahaadeeth which indicate that it is not allowed apply to the one who fears that he may fall into haraam.
From al-Sharh al-Mumti’ by Shaykh Ibn ‘Uthaymeen, 1/416-417
And Allaah knows best.